packaging: drop the aport; fp6-img installs the published apk

fp6-img no longer builds imsd from source: its images install the apk this
repo's package CI publishes to the registry (pinned version + sha256), so
the image and 'apk upgrade' carry the same binary and APKBUILD.binary is
the only imsd packaging left. The two payload files the aport carried
(kde-modem-daemon skel override, systemd preset) move up to packaging/,
where build-package.sh now takes them from.

.forgejo/workflows/package.yml

@@ -14,9 +14,10 @@ name: package
 # Release gating is the version: pkgver comes from implementations/main.cpp,
 # the registry answers 409 for an already-published version, and the publish
 # step treats that as "nothing to do" — so pushes only release when the
-# Version constant bumps. fp6-img images keep building imsd from their own
-# pinned checkout of this repo (packaging/aport/); APKBUILD.binary's payload
-# must stay identical to that aport's, so the two pipelines cannot skew.
+# Version constant bumps. This is the only producer of the imsd apk: fp6-img
+# images install the published package from the registry (pinned version,
+# pinned sha256) instead of building their own, so image and 'apk upgrade'
+# carry the same binary.
 #
 # Publishing needs PACKAGE_TOKEN (catbot account, package:write scope) — an
 # org-level secret on Catcrafts since 2026-09-02, shared with fp6-img;

implementations/main.cpp

@@ -1201,16 +1201,32 @@ private:
         call_.emplace(ctx_, rng_, uni, imsd::engine::IncomingInvite{msg}, rtpPort_);
         callReply_ = reply_;
         Log(std::format("incoming call {} from {}", uni, call_->Number()));
+        // Validate the offer BEFORE the UI hears of the call. A refused
+        // INVITE (488: nothing we can play) is answered and dropped without
+        // ever announcing it — announcing first produced a 24 ms
+        // added/terminated/deleted burst that left Plasma Dialer stuck as a
+        // lock-screen overlay with no call to show (field report 2026-09-01).
+        // The journal keeps the record: caller and reason are logged above
+        // and by the engine's teardown line.
+        auto actions = call_->OnInvite();
+        if (call_->Terminated()) {
+            Execute(actions, /*announce=*/false);
+            MaybeDropCall();
+            return;
+        }
         CallInfo info{uni, call_->Number(), "incoming", "incoming", NowEpoch(), 0,
                       "incoming"};
         PostAdded(info);
-        Execute(call_->OnInvite());
+        Execute(actions);
         MaybeDropCall();
     }
 
     // ---- action execution -------------------------------------------------
     // Returns false if a client-flow send failed (used to fail a dial's INVITE).
-    bool Execute(const std::vector<imsd::engine::Action>& actions) {
+    // `announce` false suppresses the D-Bus state/deleted events — for a call
+    // that was never announced (refused before ringing), so the bus never
+    // sees a call it cannot show.
+    bool Execute(const std::vector<imsd::engine::Action>& actions, bool announce = true) {
         using T = imsd::engine::Action::Type;
         bool sendOk = true;
         for (const auto& a : actions) {
@@ -1224,8 +1240,13 @@ private:
                     break;
                 case T::StartMedia: StartMedia(a.media); break;
                 case T::StopMedia: StopMedia(); break;
-                case T::State: PostState(call_->Uni(), a.state, a.reason); break;
-                case T::Deleted: PostDeleted(call_->Uni()); dropCall_ = true; break;
+                case T::State:
+                    if (announce) PostState(call_->Uni(), a.state, a.reason);
+                    break;
+                case T::Deleted:
+                    if (announce) PostDeleted(call_->Uni());
+                    dropCall_ = true;
+                    break;
                 case T::SetDeadline: deadline_ = Mono() + a.seconds; break;
                 case T::Log: Log(a.text); break;
             }
@@ -1257,6 +1278,7 @@ private:
             setenv("AMR_MODE", EnvOr("AMR_MODE", "2").c_str(), 1);
             setenv("DTX", EnvOr("DTX", "0").c_str(), 1);
             setenv("OCTET_ALIGN", leg.octetAlign ? "1" : "0", 1);
+            setenv("CODEC", leg.codec.c_str(), 1);
             std::vector<char*> c;
             for (auto& s : argv) c.push_back(const_cast<char*>(s.c_str()));
             c.push_back(nullptr);

implementations/media.cpp

@@ -3,28 +3,42 @@
 
 // lint-disable-file fixed-width-types no-char-pointer
 /*
-imsd-media — the RTP/AMR-WB media leg for a userspace VoLTE call, spawned as
-its own process by the daemon (imsd) exactly as the Python prototype spawned
+imsd-media — the RTP media leg for a userspace VoLTE call, spawned as its
+own process by the daemon (imsd) exactly as the Python prototype spawned
 rtpcap.py: one media leg per call, argv-configured, torn down on SIGTERM or
 when the downlink dries up. Keeping it a separate process preserves the
 far-end-hangup contract (exit code 3 = downlink RTP stopped, which on carriers
 whose network BYE never reaches our SAs is the reliable teardown trigger) and
 isolates a media crash from the control-plane daemon.
 
-Binds the advertised local RTP port, sends uplink octet-aligned AMR-WB frames
-toward the media gateway, captures the downlink, and — with PLAY=1 —
-reconstructs the media clock from RTP timestamps so pw-play stays real-time-
-paced through far-end DTX silence (every missing 20 ms slot is decoded as an
-FT-15 NO_DATA frame for CNG/PLC). MIC=1 feeds live pw-record audio through
-libvo-amrwbenc; downlink decode is libopencore-amrwb. Both codecs are dlopen'd
-so the binary has no link-time dependency on them.
+Codecs (CODEC env, set by the daemon from the negotiated SDP): AMR-WB
+(16 kHz; the mobile-to-mobile VoLTE codec, the default), AMR narrowband and
+G.711 PCMA/PCMU (8 kHz; what a PSTN gateway offers when a landline calls).
+AMR frames ride RFC 4867 payloads, octet-aligned or bandwidth-efficient
+(OCTET_ALIGN, mirrored from the SDP); G.711 is raw samples. The AMR codecs
+are dlopen'd (libvo-amrwbenc + libopencore-amrwb for WB, libopencore-amrnb
+for NB) so the binary has no link-time dependency on them; G.711 is a table.
+
+Binds the advertised local RTP port, sends uplink frames toward the media
+gateway, captures the downlink, and — with PLAY=1 — reconstructs the media
+clock from RTP timestamps so pw-play stays real-time-paced through far-end
+DTX silence (every missing 20 ms slot is decoded as a NO_DATA frame for
+CNG/PLC; zeros for G.711). MIC=1 feeds live pw-record audio through the
+encoder.
 
 Usage: imsd-media <local-ip> <rtp-port> <remote-ip> <remote-port> <pt> <secs> <out-base>
-       imsd-media --selftest   (payload pack/depay roundtrip, both formats)
-Env: MIC PLAY GAIN PLAY_GAIN AMR_MODE DTX MEDIA_TIMEOUT RTP_DUMP OCTET_ALIGN
-AUDIO_USER
+       imsd-media --selftest   (payload pack/depay roundtrip, both formats,
+                                both AMR codecs; G.711 table roundtrip)
+Env: CODEC MIC PLAY GAIN PLAY_GAIN AMR_MODE DTX MEDIA_TIMEOUT RTP_DUMP
+OCTET_ALIGN AUDIO_USER MIC_SRC PCM_DUMP
 (OCTET_ALIGN=0 selects RFC 4867 bandwidth-efficient payloads both ways; the
-daemon sets it from the negotiated SDP — 1 is the default/legacy behavior.)
+daemon sets it from the negotiated SDP — 1 is the default/legacy behavior.
+AMR_MODE is the encoder mode of whichever AMR codec is active; default 2
+for AMR-WB (12.65 kbit/s), 7 for AMR (12.2 kbit/s). MIC_SRC=<file> feeds
+raw s16 PCM at the codec rate through the encoder instead of pw-record,
+paced in real time; PCM_DUMP=1 writes the decoded downlink to <out-base>.pcm
+— both are test seams for driving the leg against a synthetic RTP peer
+with no PipeWire and no network.)
 */
 
 #include <arpa/inet.h>
@@ -46,28 +60,125 @@ double Now() {
     return std::chrono::duration<double>(Clock::now().time_since_epoch()).count();
 }
 
-// octet-aligned AMR-WB speech-frame byte sizes by frame type (mode).
-constexpr int AmrwbBytes(int ft) {
-    switch (ft) {
-        case 0: return 17; case 1: return 23; case 2: return 32; case 3: return 36;
-        case 4: return 40; case 5: return 46; case 6: return 50; case 7: return 58;
-        case 8: return 60; case 9: return 5; default: return 0;
-    }
-}
+enum class Codec { AmrWb, AmrNb, Pcma, Pcmu };
 
-// AMR-WB speech bits per frame type (RFC 4867 table 2 / TS 26.201) — the
-// exact payload bit counts of the bandwidth-efficient format. FT 14/15
-// (SPEECH_LOST/NO_DATA) carry 0 bits; unknown FTs return -1 so a corrupt
-// ToC aborts the packet instead of shifting every later bit.
-constexpr int AmrwbBits(int ft) {
+Codec ParseCodec(std::string_view name) {
+    if (name == "AMR") return Codec::AmrNb;
+    if (name == "PCMA") return Codec::Pcma;
+    if (name == "PCMU") return Codec::Pcmu;
+    return Codec::AmrWb;
+}
+std::string_view CodecName(Codec c) {
+    switch (c) {
+        case Codec::AmrWb: return "AMR-WB";
+        case Codec::AmrNb: return "AMR";
+        case Codec::Pcma: return "PCMA";
+        case Codec::Pcmu: return "PCMU";
+    }
+    return "AMR-WB";
+}
+bool IsAmr(Codec c) { return c == Codec::AmrWb || c == Codec::AmrNb; }
+// Sample rate = RTP clock rate; one 20 ms frame is 320 or 160 samples.
+int CodecRate(Codec c) { return c == Codec::AmrWb ? 16000 : 8000; }
+int FrameSamples(Codec c) { return CodecRate(c) / 50; }
+
+// AMR speech bits per frame type — the exact payload bit counts of the
+// bandwidth-efficient format. AMR-WB: RFC 4867 table 2 / TS 26.201; AMR:
+// RFC 4867 table 1 / TS 26.101 (FT 8 = SID, 9-11 = the other systems' SID
+// frames a gateway may forward). FT 14/15 (SPEECH_LOST/NO_DATA) carry 0
+// bits; unknown FTs return -1 so a corrupt ToC aborts the packet instead of
+// shifting every later bit.
+constexpr int AmrBits(Codec c, int ft) {
+    if (c == Codec::AmrWb) {
         switch (ft) {
             case 0: return 132; case 1: return 177; case 2: return 253; case 3: return 285;
             case 4: return 317; case 5: return 365; case 6: return 397; case 7: return 461;
             case 8: return 477; case 9: return 40; case 14: return 0; case 15: return 0;
             default: return -1;
         }
+    }
+    switch (ft) {
+        case 0: return 95; case 1: return 103; case 2: return 118; case 3: return 134;
+        case 4: return 148; case 5: return 159; case 6: return 204; case 7: return 244;
+        case 8: return 39; case 9: return 43; case 10: return 38; case 11: return 37;
+        case 15: return 0;
+        default: return -1;
+    }
 }
 
+// octet-aligned speech-frame byte size by frame type: the bits rounded up
+// (AMR-WB: 17 23 32 36 40 46 50 58 60, SID 5; AMR: 12 13 15 17 19 20 26 31,
+// SID 5). 0 for frame types that carry no speech.
+constexpr int AmrBytes(Codec c, int ft) {
+    int bits = AmrBits(c, ft);
+    return bits <= 0 ? 0 : (bits + 7) / 8;
+}
+
+// ---- G.711 (ITU-T, the classic Sun g711.c formulation) --------------------
+// 16-bit linear <-> 8-bit companded. Byte 0xD5 (A-law) / 0xFF (mu-law) is
+// digital zero. Idempotent: encoding a decoded sample gives the same byte.
+
+constexpr int UlawBias = 0x84;
+constexpr int UlawClip = 8159;
+
+int SegmentOf(int val, std::span<const int> ends) {
+    for (std::size_t i = 0; i < ends.size(); i++)
+        if (val <= ends[i]) return static_cast<int>(i);
+    return static_cast<int>(ends.size());
+}
+
+std::uint8_t LinearToAlaw(std::int16_t pcm) {
+    static constexpr std::array<int, 8> ends = {0x1F, 0x3F, 0x7F, 0xFF, 0x1FF, 0x3FF, 0x7FF, 0xFFF};
+    int val = pcm >> 3;  // 13-bit magnitude space
+    int mask = 0xD5;
+    if (val < 0) {
+        mask = 0x55;
+        val = -val - 1;
+    }
+    int seg = SegmentOf(val, ends);
+    if (seg >= 8) return static_cast<std::uint8_t>(0x7F ^ mask);
+    int aval = seg << 4;
+    aval |= seg < 2 ? (val >> 1) & 0x0F : (val >> seg) & 0x0F;
+    return static_cast<std::uint8_t>(aval ^ mask);
+}
+
+std::int16_t AlawToLinear(std::uint8_t a) {
+    a ^= 0x55;
+    int t = (a & 0x0F) << 4;
+    int seg = (a & 0x70) >> 4;
+    if (seg == 0) t += 8;
+    else if (seg == 1) t += 0x108;
+    else t = (t + 0x108) << (seg - 1);
+    return static_cast<std::int16_t>((a & 0x80) ? t : -t);
+}
+
+std::uint8_t LinearToUlaw(std::int16_t pcm) {
+    static constexpr std::array<int, 8> ends = {0x3F, 0x7F, 0xFF, 0x1FF, 0x3FF, 0x7FF, 0xFFF, 0x1FFF};
+    int val = pcm >> 2;  // 14-bit magnitude space
+    int mask = 0xFF;
+    if (val < 0) {
+        val = -val;
+        mask = 0x7F;
+    }
+    if (val > UlawClip) val = UlawClip;
+    val += UlawBias >> 2;
+    int seg = SegmentOf(val, ends);
+    if (seg >= 8) return static_cast<std::uint8_t>(0x7F ^ mask);
+    int uval = (seg << 4) | ((val >> (seg + 1)) & 0x0F);
+    return static_cast<std::uint8_t>(uval ^ mask);
+}
+
+std::int16_t UlawToLinear(std::uint8_t u) {
+    u = static_cast<std::uint8_t>(~u);
+    int t = ((u & 0x0F) << 3) + UlawBias;
+    t <<= (u & 0x70) >> 4;
+    return static_cast<std::int16_t>((u & 0x80) ? (UlawBias - t) : (t - UlawBias));
+}
+
+std::uint8_t G711Encode(Codec c, std::int16_t pcm) { return c == Codec::Pcma ? LinearToAlaw(pcm) : LinearToUlaw(pcm); }
+std::int16_t G711Decode(Codec c, std::uint8_t b) { return c == Codec::Pcma ? AlawToLinear(b) : UlawToLinear(b); }
+std::uint8_t G711Zero(Codec c) { return c == Codec::Pcma ? 0xD5 : 0xFF; }
+
 std::string EnvOr(const char* k, const char* d) {
     const char* v = std::getenv(k);
     return v ? std::string(v) : std::string(d);
@@ -97,62 +208,99 @@ socklen_t MakeAddr(std::string_view ip, int port, sockaddr_storage& ss) {
     return sizeof(sockaddr_in);
 }
 
-// ---- AMR-WB codecs via dlopen (vo-amrwbenc E_IF_*, opencore-amrwb D_IF_*) --
+// ---- AMR codecs via dlopen ------------------------------------------------
+// AMR-WB: vo-amrwbenc E_IF_* (encode), opencore-amrwb D_IF_* (decode).
+// AMR:    opencore-amrnb Encoder_Interface_* / Decoder_Interface_*.
+// Both families speak the RFC 4867 §5.3 storage format: [header byte][speech],
+// header = (FT << 3) | (Q << 2) — exactly the octet-aligned ToC byte with F=0.
 
 class Encoder {
 public:
-    bool Open() {
+    bool Open(Codec c, int dtx) {
+        codec_ = c;
+        if (c == Codec::AmrWb) {
             lib_ = dlopen("libvo-amrwbenc.so.0", RTLD_NOW);
             if (!lib_) return false;
-        init_ = reinterpret_cast<InitFn>(dlsym(lib_, "E_IF_init"));
-        enc_ = reinterpret_cast<EncFn>(dlsym(lib_, "E_IF_encode"));
+            wbInit_ = reinterpret_cast<WbInitFn>(dlsym(lib_, "E_IF_init"));
+            wbEnc_ = reinterpret_cast<WbEncFn>(dlsym(lib_, "E_IF_encode"));
             exit_ = reinterpret_cast<ExitFn>(dlsym(lib_, "E_IF_exit"));
-        if (!init_ || !enc_ || !exit_) return false;
-        st_ = init_();
+            if (!wbInit_ || !wbEnc_ || !exit_) return false;
+            st_ = wbInit_();
             return st_ != nullptr;
         }
-    // 320 int16 samples -> one RFC 3267 storage frame (header byte + speech).
+        lib_ = dlopen("libopencore-amrnb.so.0", RTLD_NOW);
+        if (!lib_) return false;
+        nbInit_ = reinterpret_cast<NbInitFn>(dlsym(lib_, "Encoder_Interface_init"));
+        nbEnc_ = reinterpret_cast<NbEncFn>(dlsym(lib_, "Encoder_Interface_Encode"));
+        exit_ = reinterpret_cast<ExitFn>(dlsym(lib_, "Encoder_Interface_exit"));
+        if (!nbInit_ || !nbEnc_ || !exit_) return false;
+        st_ = nbInit_(dtx);  // NB: DTX is an init-time choice
+        return st_ != nullptr;
+    }
+    // one 20 ms frame of s16 samples -> one storage frame (header byte + speech).
     std::vector<std::uint8_t> Encode(std::int16_t* samples, int mode, int dtx) {
         std::uint8_t out[128];
-        int n = enc_(st_, static_cast<std::int16_t>(mode), samples, out, static_cast<std::int16_t>(dtx));
+        int n = codec_ == Codec::AmrWb
+            ? wbEnc_(st_, static_cast<std::int16_t>(mode), samples, out, static_cast<std::int16_t>(dtx))
+            : nbEnc_(st_, mode, samples, out, 0);
         if (n <= 0) return {};
         return std::vector<std::uint8_t>(out, out + n);
     }
-    ~Encoder() { if (st_ && exit_) exit_(st_); if (lib_) dlclose(lib_); }
+    ~Encoder() {
+        if (st_ && exit_) exit_(st_);
+        if (lib_) dlclose(lib_);
+    }
 private:
-    using InitFn = void* (*)();
-    using EncFn = int (*)(void*, std::int16_t, std::int16_t*, std::uint8_t*, std::int16_t);
+    using WbInitFn = void* (*)();
+    using WbEncFn = int (*)(void*, std::int16_t, std::int16_t*, std::uint8_t*, std::int16_t);
+    using NbInitFn = void* (*)(int);
+    using NbEncFn = int (*)(void*, int, const std::int16_t*, std::uint8_t*, int);
     using ExitFn = void (*)(void*);
-    void* lib_ = nullptr; void* st_ = nullptr;
-    InitFn init_ = nullptr; EncFn enc_ = nullptr; ExitFn exit_ = nullptr;
+    Codec codec_ = Codec::AmrWb;
+    void* lib_ = nullptr;
+    void* st_ = nullptr;
+    WbInitFn wbInit_ = nullptr;
+    WbEncFn wbEnc_ = nullptr;
+    NbInitFn nbInit_ = nullptr;
+    NbEncFn nbEnc_ = nullptr;
+    ExitFn exit_ = nullptr;
 };
 
 class Decoder {
 public:
-    bool Open() {
-        lib_ = dlopen("libopencore-amrwb.so.0", RTLD_NOW);
+    bool Open(Codec c) {
+        codec_ = c;
+        bool wb = c == Codec::AmrWb;
+        lib_ = dlopen(wb ? "libopencore-amrwb.so.0" : "libopencore-amrnb.so.0", RTLD_NOW);
         if (!lib_) return false;
-        init_ = reinterpret_cast<InitFn>(dlsym(lib_, "D_IF_init"));
-        dec_ = reinterpret_cast<DecFn>(dlsym(lib_, "D_IF_decode"));
-        exit_ = reinterpret_cast<ExitFn>(dlsym(lib_, "D_IF_exit"));
+        init_ = reinterpret_cast<InitFn>(dlsym(lib_, wb ? "D_IF_init" : "Decoder_Interface_init"));
+        dec_ = reinterpret_cast<DecFn>(dlsym(lib_, wb ? "D_IF_decode" : "Decoder_Interface_Decode"));
+        exit_ = reinterpret_cast<ExitFn>(dlsym(lib_, wb ? "D_IF_exit" : "Decoder_Interface_exit"));
         if (!init_ || !dec_ || !exit_) return false;
         st_ = init_();
         return st_ != nullptr;
     }
-    // one storage frame ([header][speech]) -> 640 bytes of 16 kHz s16 PCM.
-    std::array<std::int16_t, 320> Decode(const std::uint8_t* frame, int len) {
-        std::array<std::int16_t, 320> out{};
+    // one storage frame ([header][speech]) -> one 20 ms frame of s16 PCM.
+    std::vector<std::int16_t> Decode(const std::uint8_t* frame, int len) {
+        std::vector<std::int16_t> out(static_cast<std::size_t>(FrameSamples(codec_)), 0);
         std::vector<std::uint8_t> in(frame, frame + len);
         dec_(st_, in.data(), out.data(), 0);
         return out;
     }
-    ~Decoder() { if (st_ && exit_) exit_(st_); if (lib_) dlclose(lib_); }
+    ~Decoder() {
+        if (st_ && exit_) exit_(st_);
+        if (lib_) dlclose(lib_);
+    }
 private:
     using InitFn = void* (*)();
-    using DecFn = void (*)(void*, std::uint8_t*, std::int16_t*, int);
+    using DecFn = void (*)(void*, const std::uint8_t*, std::int16_t*, int);
     using ExitFn = void (*)(void*);
-    void* lib_ = nullptr; void* st_ = nullptr;
-    InitFn init_ = nullptr; DecFn dec_ = nullptr; ExitFn exit_ = nullptr;
+    Codec codec_ = Codec::AmrWb;
+    void* lib_ = nullptr;
+    void* st_ = nullptr;
+    InitFn init_ = nullptr;
+    DecFn dec_ = nullptr;
+    ExitFn exit_ = nullptr;
 };
 
 // MSB-first bit cursor over an RTP payload (bandwidth-efficient AMR-WB is
@@ -170,10 +318,10 @@ struct BitReader {
     }
 };
 
-// bandwidth-efficient AMR-WB de-payload. Same contract as DepayOctet:
+// bandwidth-efficient AMR de-payload. Same contract as DepayOctet:
 // [(storage-header-byte, speech-bytes)...], speech re-aligned to octets.
 std::vector<std::pair<std::uint8_t, std::vector<std::uint8_t>>>
-DepayBe(std::span<const std::uint8_t> pl) {
+DepayBe(Codec c, std::span<const std::uint8_t> pl) {
     std::vector<std::pair<std::uint8_t, std::vector<std::uint8_t>>> out;
     BitReader br{pl};
     if (!br.Ok(4)) return out;
@@ -189,9 +337,9 @@ DepayBe(std::span<const std::uint8_t> pl) {
         if (!f) break;
     }
     for (auto [ft, q] : tocs) {
-        int bits = AmrwbBits(ft);
+        int bits = AmrBits(c, ft);
         if (bits < 0 || !br.Ok(static_cast<std::size_t>(bits))) break;
-        std::vector<std::uint8_t> speech(AmrwbBytes(ft), 0);
+        std::vector<std::uint8_t> speech(AmrBytes(c, ft), 0);
         for (int i = 0; i < bits; i++)
             if (br.Take(1)) speech[i >> 3] |= 0x80 >> (i & 7);
         out.emplace_back(static_cast<std::uint8_t>((ft << 3) | (q ? 0x04 : 0)), std::move(speech));
@@ -202,8 +350,8 @@ DepayBe(std::span<const std::uint8_t> pl) {
 // storage-format frame (header byte + octet-aligned speech) -> RTP payload.
 // Octet-aligned: CMR byte + the frame verbatim (the storage header doubles
 // as a ToC byte with F=0). Bandwidth-efficient: 10 header bits + exactly
-// AmrwbBits(ft) speech bits, final octet zero-padded.
-std::vector<std::uint8_t> PayloadFromFrame(std::span<const std::uint8_t> frame, bool octetAlign) {
+// AmrBits(ft) speech bits, final octet zero-padded.
+std::vector<std::uint8_t> PayloadFromFrame(Codec c, std::span<const std::uint8_t> frame, bool octetAlign) {
     if (octetAlign) {
         std::vector<std::uint8_t> pl = {0xF0};
         pl.insert(pl.end(), frame.begin(), frame.end());
@@ -211,7 +359,7 @@ std::vector<std::uint8_t> PayloadFromFrame(std::span<const std::uint8_t> frame,
     }
     int ft = (frame[0] >> 3) & 0x0F;
     int q = (frame[0] >> 2) & 1;
-    int bits = AmrwbBits(ft);
+    int bits = AmrBits(c, ft);
     if (bits < 0) bits = 0;
     std::vector<std::uint8_t> pl((10 + bits + 7) / 8, 0);
     auto put = [&](int pos, int n, std::uint32_t v) {
@@ -227,10 +375,10 @@ std::vector<std::uint8_t> PayloadFromFrame(std::span<const std::uint8_t> frame,
     return pl;
 }
 
-// octet-aligned AMR-WB de-payload: skip CMR, read ToC bytes until F=0, then
+// octet-aligned AMR de-payload: skip CMR, read ToC bytes until F=0, then
 // the speech runs. Returns [(storage-header-byte, speech-bytes)...].
 std::vector<std::pair<std::uint8_t, std::vector<std::uint8_t>>>
-DepayOctet(std::span<const std::uint8_t> pl) {
+DepayOctet(Codec c, std::span<const std::uint8_t> pl) {
     std::vector<std::pair<std::uint8_t, std::vector<std::uint8_t>>> out;
     if (pl.empty()) return out;
     std::size_t i = 1;  // skip CMR
@@ -242,7 +390,7 @@ DepayOctet(std::span<const std::uint8_t> pl) {
     }
     for (std::uint8_t toc : tocs) {
         int ft = (toc >> 3) & 0x0F;
-        int n = AmrwbBytes(ft);
+        int n = AmrBytes(c, ft);
         std::vector<std::uint8_t> speech;
         if (n > 0 && i + n <= pl.size()) speech.assign(pl.begin() + i, pl.begin() + i + n);
         out.emplace_back(static_cast<std::uint8_t>(toc & 0x7C), std::move(speech));
@@ -267,7 +415,7 @@ std::size_t RtpPayloadOffset(std::span<const std::uint8_t> pkt) {
 // is postmarketOS's standard account. `toChild` true = we write the child's
 // stdin (pw-play); false = we read its stdout (pw-record). Returns {pid, fd}.
 struct Child { pid_t pid = -1; int fd = -1; };
-Child SpawnPw(bool play, bool toChild) {
+Child SpawnPw(bool play, bool toChild, int rate) {
     int pipefd[2];
     if (pipe(pipefd) != 0) return {};
     std::vector<std::string> argv;
@@ -280,7 +428,8 @@ Child SpawnPw(bool play, bool toChild) {
     }
     const char* tool = play ? "pw-play" : "pw-record";
     const char* lat = play ? "40ms" : "20ms";
-    for (const char* a : {tool, "--raw", "--rate", "16000", "--channels", "1", "--format", "s16", "--latency", lat, "-"})
+    std::string rateStr = std::to_string(rate);
+    for (const char* a : {tool, "--raw", "--rate", rateStr.c_str(), "--channels", "1", "--format", "s16", "--latency", lat, "-"})
         argv.emplace_back(a);
     pid_t pid = fork();
     if (pid == 0) {
@@ -315,6 +464,7 @@ bool ReadExact(int fd, std::uint8_t* buf, std::size_t n) {
 struct TxState {
     std::mutex lock;
     int pt = 0;
+    std::uint32_t tsStep = 320;  // samples per 20 ms frame at the codec's clock
     std::uint32_t ssrc = 0x5EED1234;
     std::uint32_t seq = 1000;
     std::uint32_t ts = 160000;
@@ -338,7 +488,7 @@ void RtpSend(int sock, TxState& st, std::span<const std::uint8_t> payload) {
         hdr[8] = (st.ssrc >> 24) & 0xFF; hdr[9] = (st.ssrc >> 16) & 0xFF;
         hdr[10] = (st.ssrc >> 8) & 0xFF; hdr[11] = st.ssrc & 0xFF;
         st.seq = (st.seq + 1) & 0xFFFF;
-        st.ts = (st.ts + 320) & 0xFFFFFFFF;
+        st.ts = (st.ts + st.tsStep) & 0xFFFFFFFF;
         a1 = st.dst; l1 = st.dstLen; a2 = st.latched; l2 = st.latchedLen;
     }
     std::vector<std::uint8_t> pkt(hdr, hdr + 12);
@@ -355,15 +505,34 @@ void RtpSend(int sock, TxState& st, std::span<const std::uint8_t> payload) {
 }
 
 std::vector<std::pair<std::uint8_t, std::vector<std::uint8_t>>>
-Depay(std::span<const std::uint8_t> pl, bool octetAlign) {
-    return octetAlign ? DepayOctet(pl) : DepayBe(pl);
+Depay(Codec c, std::span<const std::uint8_t> pl, bool octetAlign) {
+    return octetAlign ? DepayOctet(c, pl) : DepayBe(c, pl);
 }
 
-std::vector<std::uint8_t> SilenceFrame(int ft, bool octetAlign) {
-    // storage frame: ToC(F=0,FT,Q=1) + zeroed speech, payloaded per mode.
+// What goes out every 20 ms while the mic is not feeding frames: for AMR a
+// storage frame ToC(F=0,FT,Q=1) + zeroed speech, payloaded per mode; for
+// G.711 one frame of digital zero.
+std::vector<std::uint8_t> SilenceFrame(Codec c, int ft, bool octetAlign) {
+    if (!IsAmr(c)) return std::vector<std::uint8_t>(static_cast<std::size_t>(FrameSamples(c)), G711Zero(c));
     std::vector<std::uint8_t> f = {static_cast<std::uint8_t>((ft << 3) | 0x04)};
-    f.resize(1 + AmrwbBytes(ft), 0);
-    return PayloadFromFrame(f, octetAlign);
+    f.resize(1 + static_cast<std::size_t>(AmrBytes(c, ft)), 0);
+    return PayloadFromFrame(c, f, octetAlign);
+}
+
+// G.711 uplink: one 20 ms frame of samples -> one payload of companded bytes.
+std::vector<std::uint8_t> G711Payload(Codec c, std::span<const std::int16_t> pcm) {
+    std::vector<std::uint8_t> pl(pcm.size());
+    for (std::size_t i = 0; i < pcm.size(); i++)
+        pl[i] = G711Encode(c, pcm[i]);
+    return pl;
+}
+
+// G.711 downlink: one frame's worth of companded bytes -> PCM.
+std::vector<std::int16_t> G711DecodeFrame(Codec c, std::span<const std::uint8_t> bytes) {
+    std::vector<std::int16_t> pcm(bytes.size());
+    for (std::size_t i = 0; i < bytes.size(); i++)
+        pcm[i] = G711Decode(c, bytes[i]);
+    return pcm;
 }
 
 std::atomic<bool> Quit{false};
@@ -372,31 +541,64 @@ void OnSig(int) { Quit.store(true); }
 // playout queue item
 struct PktItem { std::uint32_t ts; std::vector<std::uint8_t> payload; };
 
-}  // namespace
-
-int main(int argc, char** argv) {
-    if (argc == 2 && std::string_view(argv[1]) == "--selftest") {
-        // pack->depay roundtrip of every frame type, both payload formats.
-        // BE carries exactly AmrwbBits(ft) bits, so the pattern's padding
+// --selftest: pack->depay roundtrip of every frame type, both payload
+// formats, both AMR codecs; G.711 digital zero, idempotence over the whole
+// 16-bit range, and a 1 kHz sine surviving with the codec's nominal SNR.
+int SelfTest() {
+    for (Codec c : {Codec::AmrWb, Codec::AmrNb}) {
+        for (int ft = 0; ft < 16; ft++) {
+            int bits = AmrBits(c, ft);
+            if (bits <= 0) continue;
+            // BE carries exactly AmrBits(ft) bits, so the pattern's padding
             // bits in the last speech byte must be zero for equality to hold.
-        for (int ft : {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}) {
-            std::vector<std::uint8_t> frame = {
-                static_cast<std::uint8_t>((ft << 3) | 0x04)};
-            int bits = AmrwbBits(ft);
-            for (int i = 0; i < AmrwbBytes(ft); i++)
+            std::vector<std::uint8_t> frame = {static_cast<std::uint8_t>((ft << 3) | 0x04)};
+            for (int i = 0; i < AmrBytes(c, ft); i++)
                 frame.push_back(static_cast<std::uint8_t>(0xA5 + i * 31));
             if (bits % 8) frame.back() &= static_cast<std::uint8_t>(0xFF << (8 - bits % 8));
             for (bool oa : {true, false}) {
-                auto got = Depay(PayloadFromFrame(frame, oa), oa);
+                auto got = Depay(c, PayloadFromFrame(c, frame, oa), oa);
                 if (got.size() != 1 || got[0].first != frame[0] || !std::equal(got[0].second.begin(), got[0].second.end(), frame.begin() + 1, frame.end())) {
-                    std::println(std::cerr, "selftest FAIL ft={} oa={}", ft, oa);
+                    std::println(std::cerr, "selftest FAIL {} ft={} oa={}", CodecName(c), ft, oa);
                     return 1;
                 }
             }
         }
+    }
+    if (LinearToAlaw(0) != 0xD5 || LinearToUlaw(0) != 0xFF) {
+        std::println(std::cerr, "selftest FAIL G.711 digital zero");
+        return 1;
+    }
+    for (Codec c : {Codec::Pcma, Codec::Pcmu}) {
+        for (int v = -32768; v <= 32767; v++) {
+            std::uint8_t b = G711Encode(c, static_cast<std::int16_t>(v));
+            if (G711Encode(c, G711Decode(c, b)) != b) {
+                std::println(std::cerr, "selftest FAIL {} not idempotent at {}", CodecName(c), v);
+                return 1;
+            }
+        }
+        double sig = 0;
+        double err = 0;
+        for (int i = 0; i < 8000; i++) {
+            double x = 10000.0 * std::sin(2 * std::numbers::pi * 1000.0 * i / 8000.0);
+            auto sample = static_cast<std::int16_t>(std::lround(x));
+            std::int16_t d = G711Decode(c, G711Encode(c, sample));
+            sig += x * x;
+            err += (x - d) * (x - d);
+        }
+        double snr = 10 * std::log10(sig / err);
+        if (snr < 30) {
+            std::println(std::cerr, "selftest FAIL {} sine SNR {:.1f} dB", CodecName(c), snr);
+            return 1;
+        }
+    }
     std::println("selftest OK");
     return 0;
-    }
+}
+
+}  // namespace
+
+int main(int argc, char** argv) {
+    if (argc == 2 && std::string_view(argv[1]) == "--selftest") return SelfTest();
     if (argc < 8) {
         std::println(std::cerr, "usage: imsd-media local rtp_port remote_ip remote_port pt secs out");
         return 2;
@@ -409,25 +611,35 @@ int main(int argc, char** argv) {
     double secs = std::atof(argv[6]);
     std::string out = argv[7];
 
+    Codec codec = ParseCodec(EnvOr("CODEC", "AMR-WB"));
+    bool amr = IsAmr(codec);
+    int rate = CodecRate(codec);
+    auto frameSamples = static_cast<std::size_t>(FrameSamples(codec));
     bool mic = EnvBool("MIC", false);
     bool play = EnvBool("PLAY", false);
-    int amrMode = std::atoi(EnvOr("AMR_MODE", "2").c_str());
+    int amrMode = std::atoi(EnvOr("AMR_MODE", codec == Codec::AmrWb ? "2" : "7").c_str());
     double gain = std::atof(EnvOr("GAIN", "1.0").c_str());
     double playGain = std::atof(EnvOr("PLAY_GAIN", "1.0").c_str());
     int dtx = EnvBool("DTX", false) ? 1 : 0;
     bool octetAlign = EnvBool("OCTET_ALIGN", true);
     double mediaTimeout = std::atof(EnvOr("MEDIA_TIMEOUT", "6.0").c_str());
     bool rtpDump = EnvBool("RTP_DUMP", false);
+    std::string micSrc = EnvOr("MIC_SRC", "");
+    bool pcmDump = EnvBool("PCM_DUMP", false);
     constexpr int ExitMediaTimeout = 3;
     constexpr int PrimeFrames = 8;
     constexpr int MaxFill = 25;
     constexpr std::size_t PlayqMax = 256;
 
     int sock = socket(Is6(local) ? AF_INET6 : AF_INET, SOCK_DGRAM, 0);
-    if (sock < 0) { std::println(std::cerr, "imsd-media: socket failed"); return 1; }
+    if (sock < 0) {
+        std::println(std::cerr, "imsd-media: socket failed");
+        return 1;
+    }
     int one = 1;
     setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &one, sizeof one);
-    sockaddr_storage bindA; socklen_t bindL = MakeAddr(local, rtpPort, bindA);
+    sockaddr_storage bindA;
+    socklen_t bindL = MakeAddr(local, rtpPort, bindA);
     if (bind(sock, reinterpret_cast<sockaddr*>(&bindA), bindL) != 0) {
         std::println(std::cerr, "imsd-media: bind [{}]:{} failed", local, rtpPort);
         return 1;
@@ -437,63 +649,98 @@ int main(int argc, char** argv) {
 
     TxState st;
     st.pt = pt;
+    st.tsStep = static_cast<std::uint32_t>(frameSamples);
     st.dstLen = MakeAddr(rIp, rPort, st.dst);
-    st.latched = st.dst; st.latchedLen = st.dstLen;
+    st.latched = st.dst;
+    st.latchedLen = st.dstLen;
 
     signal(SIGTERM, OnSig);
     signal(SIGINT, OnSig);
     signal(SIGPIPE, SIG_IGN);
 
-    // ---- mic uplink thread
+    // ---- mic uplink thread: pw-record (or the MIC_SRC file, real-time paced)
+    // through the codec's encoder, one RTP packet per 20 ms frame
     std::atomic<bool> stop{false};
     std::jthread micThread;
     if (mic) {
         micThread = std::jthread([&] {
             Encoder enc;
-            if (!enc.Open()) {
-                std::println(std::cerr, "imsd-media: mic: encoder unavailable; silence fallback");
+            if (amr && !enc.Open(codec, dtx)) {
+                std::println(std::cerr, "imsd-media: mic: {} encoder unavailable; silence fallback", CodecName(codec));
                 return;
             }
-            Child rec = SpawnPw(false, /*toChild=*/false);
+            int fd = -1;
+            pid_t pid = -1;
+            if (!micSrc.empty()) {
+                fd = open(micSrc.c_str(), O_RDONLY);
+                if (fd < 0) {
+                    std::println(std::cerr, "imsd-media: mic: cannot open MIC_SRC {}", micSrc);
+                    return;
+                }
+            } else {
+                Child rec = SpawnPw(false, /*toChild=*/false, rate);
                 if (rec.pid < 0) return;
-            std::uint8_t raw[640];
+                fd = rec.fd;
+                pid = rec.pid;
+            }
+            std::vector<std::uint8_t> raw(frameSamples * 2);
+            std::vector<std::int16_t> samples(frameSamples);
+            auto next = Clock::now();
             while (!stop.load()) {
-                if (!ReadExact(rec.fd, raw, 640)) {
-                    std::println(std::cerr, "imsd-media: mic: pw-record EOF; silence fallback");
+                if (!ReadExact(fd, raw.data(), raw.size())) {
+                    std::println(std::cerr, "imsd-media: mic: {} EOF; silence fallback", pid > 0 ? "pw-record" : "MIC_SRC");
                     break;
                 }
-                std::int16_t samples[320];
-                std::memcpy(samples, raw, 640);
-                if (gain != 1.0)
-                    for (int i = 0; i < 320; i++) {
-                        int v = static_cast<int>(samples[i] * gain);
-                        samples[i] = static_cast<std::int16_t>(v < -32768 ? -32768 : (v > 32767 ? 32767 : v));
+                if (pid < 0) {
+                    // a file delivers instantly; pace it like a microphone
+                    next += std::chrono::milliseconds(20);
+                    std::this_thread::sleep_until(next);
                 }
-                std::vector<std::uint8_t> frame = enc.Encode(samples, amrMode, dtx);
+                std::memcpy(samples.data(), raw.data(), raw.size());
+                if (gain != 1.0)
+                    for (auto& sample : samples) {
+                        int v = static_cast<int>(sample * gain);
+                        sample = static_cast<std::int16_t>(v < -32768 ? -32768 : (v > 32767 ? 32767 : v));
+                    }
+                std::vector<std::uint8_t> payload;
+                if (amr) {
+                    std::vector<std::uint8_t> frame = enc.Encode(samples.data(), amrMode, dtx);
                     if (frame.empty()) continue;
+                    payload = PayloadFromFrame(codec, frame, octetAlign);
+                } else {
+                    payload = G711Payload(codec, samples);
+                }
                 st.micOn.store(true);
                 { std::scoped_lock g(st.lock); st.txMic++; }
-                RtpSend(sock, st, PayloadFromFrame(frame, octetAlign));
+                RtpSend(sock, st, payload);
             }
             st.micOn.store(false);
-            close(rec.fd);
-            kill(rec.pid, SIGKILL);
-            waitpid(rec.pid, nullptr, 0);
+            close(fd);
+            if (pid > 0) {
+                kill(pid, SIGKILL);
+                waitpid(pid, nullptr, 0);
+            }
         });
     }
 
-    // ---- downlink playout (decode + RTP-timestamp clock reconstruction)
+    // ---- downlink playout (decode + RTP-timestamp clock reconstruction).
+    // Runs for pw-play (PLAY=1) and/or the PCM dump (PCM_DUMP=1).
     Decoder dec;
     Child playCh;
     bool playOn = false;
+    bool decodeOn = false;
+    if (play || pcmDump) {
+        if (!amr || dec.Open(codec)) {
             if (play) {
-        if (dec.Open()) {
-            playCh = SpawnPw(true, /*toChild=*/true);
+                playCh = SpawnPw(true, /*toChild=*/true, rate);
                 playOn = playCh.pid >= 0;
+            }
+            decodeOn = playOn || pcmDump;
         } else {
-            std::println(std::cerr, "imsd-media: play: decoder unavailable; capture only");
+            std::println(std::cerr, "imsd-media: play: {} decoder unavailable; capture only", CodecName(codec));
         }
     }
+    std::FILE* pcmFile = decodeOn && pcmDump ? std::fopen((std::format("{}.pcm", out)).c_str(), "wb") : nullptr;
     std::mutex qlock;
     std::condition_variable qcv;
     std::deque<PktItem> playq;
@@ -502,9 +749,11 @@ int main(int argc, char** argv) {
     std::uint64_t late = 0;
     std::uint64_t qdrop = 0;
     std::jthread playThread;
-    if (playOn) {
+    if (decodeOn) {
         playThread = std::jthread([&] {
             auto writePcm = [&](std::span<const std::int16_t> pcm) {
+                if (pcmFile) std::fwrite(pcm.data(), 2, pcm.size(), pcmFile);
+                if (!playOn) return true;
                 std::size_t bytes = pcm.size() * 2;
                 const char* p = reinterpret_cast<const char*>(pcm.data());
                 std::size_t off = 0;
@@ -515,14 +764,20 @@ int main(int argc, char** argv) {
                 }
                 return true;
             };
-            auto applyGain = [&](std::array<std::int16_t, 320>& pcm) {
+            auto applyGain = [&](std::vector<std::int16_t>& pcm) {
                 if (playGain == 1.0) return;
-                for (auto& s : pcm) {
-                    int v = static_cast<int>(s * playGain);
-                    s = static_cast<std::int16_t>(v < -32768 ? -32768 : (v > 32767 ? 32767 : v));
+                for (auto& sample : pcm) {
+                    int v = static_cast<int>(sample * playGain);
+                    sample = static_cast<std::int16_t>(v < -32768 ? -32768 : (v > 32767 ? 32767 : v));
                 }
             };
-            std::array<std::int16_t, 320> zero{};
+            // Decoder state is time-ordered: the CNG fill for a gap must be
+            // decoded BEFORE the frames that follow the gap, so depay first,
+            // decode in playout order.
+            auto decodeFrame = [&](std::span<const std::uint8_t> f) {
+                return amr ? dec.Decode(f.data(), static_cast<int>(f.size())) : G711DecodeFrame(codec, f);
+            };
+            std::vector<std::int16_t> zero(frameSamples, 0);
             std::optional<std::uint32_t> expect;
             for (;;) {
                 PktItem item;
@@ -533,7 +788,18 @@ int main(int argc, char** argv) {
                     item = std::move(playq.front());
                     playq.pop_front();
                 }
-                auto frames = Depay(item.payload, octetAlign);
+                std::vector<std::vector<std::uint8_t>> frames;
+                if (amr) {
+                    for (auto& [hdr, speech] : Depay(codec, item.payload, octetAlign)) {
+                        std::vector<std::uint8_t> f = {hdr};
+                        f.insert(f.end(), speech.begin(), speech.end());
+                        frames.push_back(std::move(f));
+                    }
+                } else {
+                    // whole frames back to back (a gateway may pack 2 at ptime 40)
+                    for (std::size_t off = 0; off + frameSamples <= item.payload.size(); off += frameSamples)
+                        frames.emplace_back(item.payload.begin() + static_cast<std::ptrdiff_t>(off), item.payload.begin() + static_cast<std::ptrdiff_t>(off + frameSamples));
+                }
                 if (frames.empty()) continue;
                 int fill = 0;
                 if (!expect) {
@@ -541,36 +807,39 @@ int main(int argc, char** argv) {
                         if (!writePcm(zero)) return;
                 } else {
                     std::uint32_t diff = (item.ts - *expect) & 0xFFFFFFFF;
-                    if (diff >= 0x80000000u) { late++; continue; }
-                    fill = static_cast<int>(diff / 320);
+                    if (diff >= 0x80000000u) {
+                        late++;
+                        continue;
+                    }
+                    fill = static_cast<int>(diff / frameSamples);
                     if (fill > MaxFill) fill = 0;
                 }
                 for (int i = 0; i < fill; i++) {
                     cng++;
                     std::uint8_t nodata = 0x7C;
-                    auto pcm = dec.Decode(&nodata, 1);
+                    std::vector<std::int16_t> pcm = amr ? dec.Decode(&nodata, 1) : zero;
                     applyGain(pcm);
                     if (!writePcm(pcm)) return;
                 }
-                for (auto& [hdr, speech] : frames) {
+                for (auto& f : frames) {
                     rxPlayed++;
-                    std::vector<std::uint8_t> f = {hdr};
-                    f.insert(f.end(), speech.begin(), speech.end());
-                    auto pcm = dec.Decode(f.data(), static_cast<int>(f.size()));
+                    std::vector<std::int16_t> pcm = decodeFrame(f);
                     applyGain(pcm);
                     if (!writePcm(pcm)) return;
                 }
-                expect = (item.ts + 320 * static_cast<std::uint32_t>(frames.size())) & 0xFFFFFFFF;
+                expect = (item.ts + static_cast<std::uint32_t>(frameSamples * frames.size())) & 0xFFFFFFFF;
             }
         });
     }
 
     // ---- main recv loop
-    std::vector<std::uint8_t> silence = SilenceFrame(0, octetAlign);
+    std::vector<std::uint8_t> silence = SilenceFrame(codec, 0, octetAlign);
     for (int i = 0; i < 5; i++) RtpSend(sock, st, silence);  // latch burst
 
     std::FILE* dump = rtpDump ? std::fopen((std::format("{}.rtp", out)).c_str(), "wb") : nullptr;
-    double t0 = Now(), lastTx = 0, lastRx = Now();
+    double t0 = Now();
+    double lastTx = 0;
+    double lastRx = Now();
     std::uint64_t rx = 0;
     std::uint64_t rxBytes = 0;
     bool gotMedia = false;
@@ -588,7 +857,8 @@ int main(int argc, char** argv) {
             lastTx = now;
         }
         std::uint8_t buf[65535];
-        sockaddr_storage src; socklen_t srcLen = sizeof src;
+        sockaddr_storage src;
+        socklen_t srcLen = sizeof src;
         ssize_t n = recvfrom(sock, buf, sizeof buf, 0, reinterpret_cast<sockaddr*>(&src), &srcLen);
         if (n <= 0) continue;
         lastRx = Now();
@@ -626,7 +896,10 @@ int main(int argc, char** argv) {
             std::uint32_t pktTs = (static_cast<std::uint32_t>(buf[4]) << 24) |
                                   (buf[5] << 16) | (buf[6] << 8) | buf[7];
             std::scoped_lock g(qlock);
-            if (playq.size() >= PlayqMax) { playq.pop_front(); qdrop++; }
+            if (playq.size() >= PlayqMax) {
+                playq.pop_front();
+                qdrop++;
+            }
             playq.push_back({pktTs, std::vector<std::uint8_t>(buf + off, buf + n)});
             qcv.notify_one();
         }
@@ -637,6 +910,7 @@ int main(int argc, char** argv) {
     if (micThread.joinable()) micThread.join();
     if (playThread.joinable()) playThread.join();
     if (dump) std::fclose(dump);
+    if (pcmFile) std::fclose(pcmFile);
     if (playOn) {
         close(playCh.fd);
         int status;
@@ -652,14 +926,14 @@ int main(int argc, char** argv) {
     // .stats sidecar (tiny; always written)
     if (std::FILE* sf = std::fopen((std::format("{}.stats", out)).c_str(), "w")) {
         std::print(sf,
-            "{{\"tx\": {}, \"tx_mic\": {}, \"rx\": {}, \"rx_bytes\": {}, "
+            "{{\"codec\": \"{}\", \"tx\": {}, \"tx_mic\": {}, \"rx\": {}, \"rx_bytes\": {}, "
             "\"rx_played\": {}, \"cng\": {}, \"late\": {}, \"qdrop\": {}, "
             "\"first_src\": \"{}\", \"dst\": \"{}:{}\", \"pt\": {}, \"mic\": {}, "
             "\"play\": {}, \"amr_mode\": {}, \"media_ended\": {}}}",
-            st.tx, st.txMic, rx, rxBytes, rxPlayed, cng, late, qdrop, firstSrc,
+            CodecName(codec), st.tx, st.txMic, rx, rxBytes, rxPlayed, cng, late, qdrop, firstSrc,
             rIp, rPort, pt, mic, play, amrMode, mediaEnded);
         std::fclose(sf);
     }
-    std::println("imsd-media: tx={} tx_mic={} rx={} rx_played={} cng={} late={} " "qdrop={} rx_bytes={} first_src={} media_ended={}", st.tx, st.txMic, rx, rxPlayed, cng, late, qdrop, rxBytes, firstSrc, mediaEnded);
+    std::println("imsd-media: codec={} tx={} tx_mic={} rx={} rx_played={} cng={} late={} " "qdrop={} rx_bytes={} first_src={} media_ended={}", CodecName(codec), st.tx, st.txMic, rx, rxPlayed, cng, late, qdrop, rxBytes, firstSrc, mediaEnded);
     return mediaEnded ? ExitMediaTimeout : 0;
 }

interfaces/Imsd-Engine.cppm

@@ -52,7 +52,8 @@ export namespace imsd::engine {
         return d == Direction::Incoming ? "incoming" : "outgoing";
     }
 
-    // Parsed SDP answer needed to bring up the media leg.
+    // Parsed SDP answer needed to bring up the media leg. `codec` is one of
+    // imsd-media's: "AMR-WB", "AMR", "PCMA", "PCMU" (empty = none we play).
     struct MediaLeg {
         std::string remoteIp;
         int remotePort = 0;
@@ -156,16 +157,20 @@ export namespace imsd::engine {
 
         // UAS: answer the inbound INVITE with 100 Trying + 180 Ringing (made
         // reliable only when the caller Requires 100rel) and arm the ring
-        // timeout. An offer we cannot serve — no audio line, or no AMR-WB
-        // (the media plane is AMR-WB-only) — is refused with 488 up front,
-        // before the UI ever rings.
+        // timeout. An offer we cannot serve — no audio line, or none of the
+        // codecs imsd-media plays (AMR-WB, AMR, PCMA, PCMU) — is refused
+        // with 488 up front, before the UI ever rings; the log line names
+        // what WAS offered, so a field journal answers "which codec did the
+        // gateway want" without a raw SIP dump.
         std::vector<Action> OnInvite() {
             std::vector<Action> a;
             if (direction_ != Direction::Incoming || state_ != CallState::Incoming) return a;
             MediaLeg leg = ParseAnswer();
-            if (!leg.Valid() || leg.codec != "AMR-WB") {
+            if (!leg.Valid() || leg.codec.empty()) {
                 a.push_back(Respond(imsd::msg::BuildInviteResponse(ctx_, invite_, 488, "Not Acceptable Here", d_.itag)));
-                Append(a, Finish("error", "incoming offer unusable (need AMR-WB audio); 488 sent"));
+                std::string why = !leg.Valid() ? "no usable audio line"
+                                               : std::format("no playable codec, offered: {}", imsd::sdp::OfferedCodecs(answerSdp_));
+                Append(a, Finish("error", std::format("incoming offer unusable ({}); 488 sent", why)));
                 return a;
             }
             a.push_back(Respond(imsd::msg::BuildInviteResponse(ctx_, invite_, 100, "Trying", d_.itag)));
@@ -196,7 +201,7 @@ export namespace imsd::engine {
             spec.payloadType = leg.payloadType;
             spec.octetAlign = leg.octetAlign;
             spec.codec = leg.codec;
-            spec.dtmfPt = imsd::sdp::TelephoneEventPt(Body(invite_), 16000);
+            spec.dtmfPt = imsd::sdp::TelephoneEventPt(Body(invite_), imsd::sdp::CodecRate(leg.codec));
             localSdp_ = imsd::sdp::BuildAnswer(spec);
             // session timers: echo the caller's Session-Expires; with no
             // refresher stated, make the caller (uac) the refresher — its

interfaces/Imsd-Sdp.cppm

@@ -3,17 +3,20 @@
 
 // lint-disable-file fixed-width-types
 /*
-Imsd:Sdp — AMR-WB SDP offer/answer building + parsing.
+Imsd:Sdp — SDP offer/answer building + parsing for the voice media plane.
 
-The offer is a fixed AMR-WB (octet-aligned) + telephone-event shape with an
-optional GSMA IR.92 QoS-precondition block; it is what commercial IMS cores
-expect from a VoLTE UE, and its exact bytes are pinned by tests/Sdp. The
+The offer is a fixed AMR-WB (octet-aligned) + AMR + telephone-event shape
+with an optional GSMA IR.92 QoS-precondition block; it is what commercial IMS
+cores expect from a VoLTE UE, and its exact bytes are pinned by tests/Sdp. The
 parser extracts only what the media plane needs: remote address/port, the
-negotiated payload type, and octet-align mode — it reads answers to our
-offers and inbound offers alike (same fields either way). BuildAnswer is the
-terminating side: it answers an inbound offer with the offer's own payload
-type numbers (RFC 3264) and mirrors its octet-align mode (RFC 4867 requires
-both directions to use one mode). Pure std C++.
+negotiated payload type, the codec and octet-align mode — it reads answers
+to our offers and inbound offers alike (same fields either way). The codecs
+it knows are the ones imsd-media can play: AMR-WB, AMR (narrowband) and
+G.711 (PCMA/PCMU) — the last two are what a PSTN gateway offers when a
+landline calls. BuildAnswer is the terminating side: it answers an inbound
+offer with the offer's own payload type numbers (RFC 3264) and mirrors its
+octet-align mode (RFC 4867 requires both directions to use one mode). Pure
+std C++.
 */
 
 export module Imsd:Sdp;
@@ -54,7 +57,11 @@ export namespace imsd::sdp {
         std::string currRemote = "none";  // a=curr:qos remote <this>
     };
 
-    // AMR-WB (octet-aligned) offer. Byte layout is pinned by tests/Sdp.
+    // Our offer: AMR-WB (octet-aligned) first, AMR narrowband second — the
+    // 3GPP-mandatory codec every IMS core and PSTN gateway can answer, so a
+    // call we place TO a landline no longer depends on the far side
+    // transcoding up to wideband — each with telephone-event at its own
+    // clock. Byte layout is pinned by tests/Sdp.
     std::string BuildOffer(const Offer& o) {
         std::string ipver = Is6(o.local) ? "IP6" : "IP4";
         std::string s;
@@ -63,14 +70,18 @@ export namespace imsd::sdp {
         s += "s=-\r\n";
         s += std::format("c=IN {} {}\r\n", ipver, o.local);
         s += "t=0 0\r\n";
-        s += std::format("m=audio {} RTP/AVP 97 98\r\n", o.rtpPort);
+        s += std::format("m=audio {} RTP/AVP 97 99 98 100\r\n", o.rtpPort);
         s += "b=AS:41\r\n";
         s += "b=RS:512\r\n";
         s += "b=RR:1536\r\n";
         s += "a=rtpmap:97 AMR-WB/16000/1\r\n";
         s += "a=fmtp:97 octet-align=1;mode-change-capability=2;max-red=0\r\n";
+        s += "a=rtpmap:99 AMR/8000/1\r\n";
+        s += "a=fmtp:99 octet-align=1;mode-change-capability=2;max-red=0\r\n";
         s += "a=rtpmap:98 telephone-event/16000\r\n";
         s += "a=fmtp:98 0-15\r\n";
+        s += "a=rtpmap:100 telephone-event/8000\r\n";
+        s += "a=fmtp:100 0-15\r\n";
         s += "a=ptime:20\r\n";
         s += "a=maxptime:240\r\n";
         if (o.precond) {
@@ -88,18 +99,60 @@ export namespace imsd::sdp {
         int port = -1;                  // -1 = no m=audio line found
         int payloadType = -1;
         bool octetAlign = false;
-        std::string codec = "AMR-WB";
+        std::string codec = "AMR-WB";   // "AMR-WB" | "AMR" | "PCMA" | "PCMU" | "" (none we play)
     };
 
+    // The encoding name an offer gives a payload type: its a=rtpmap line,
+    // upper-cased (RFC 4566 §6: encoding names are case-insensitive), else
+    // the static assignment for 0/8 (RFC 3551 §6 — a G.711 offer may carry
+    // no rtpmap at all). Empty when neither applies.
+    std::string CodecName(std::string_view body, int pt) {
+        std::string key = std::format("a=rtpmap:{} ", pt);
+        if (auto at = Find(body, key)) {
+            std::size_t nameBegin = *at + key.size();
+            std::size_t nameEnd = body.find_first_of("/\r\n", nameBegin);
+            std::string name(body.substr(nameBegin, nameEnd == std::string_view::npos ? std::string_view::npos : nameEnd - nameBegin));
+            for (char& c : name)
+                c = static_cast<char>(std::toupper(static_cast<unsigned char>(c)));
+            return name;
+        }
+        if (pt == 0) return "PCMU";
+        if (pt == 8) return "PCMA";
+        return "";
+    }
+
+    // The offer's audio payload types with their names, "8 PCMA, 96 AMR,
+    // 101 telephone-event" — for the log line of a refused offer, so a
+    // field journal says WHAT the gateway offered without a raw SIP dump.
+    std::string OfferedCodecs(std::string_view body) {
+        auto m = Find(body, "m=audio ");
+        if (!m) return "no m=audio line";
+        std::size_t lineEnd = body.find_first_of("\r\n", *m);
+        std::string_view line = body.substr(*m, lineEnd == std::string_view::npos ? std::string_view::npos : lineEnd - *m);
+        std::string out;
+        int field = 0;
+        for (auto part : std::views::split(line, ' ')) {
+            std::string_view tok(part);
+            if (field++ < 3 || tok.empty()) continue;  // m=audio <port> <proto> <pt>...
+            auto pt = ParseInt(tok);
+            if (!pt) continue;
+            std::string name = CodecName(body, *pt);
+            if (!out.empty()) out += ", ";
+            out += name.empty() ? std::format("{}", *pt) : std::format("{} {}", *pt, name);
+        }
+        return out.empty() ? std::string(line) : out;
+    }
+
     // Payload-type preference: AMR-WB with octet-align=1 > AMR-WB > AMR with
-    // octet-align=1 > AMR. Octet-aligned wins within a codec because it is
-    // the media leg's native, call-proven format (bandwidth-efficient is
-    // supported but was the s56 static-audio culprit) — when the peer offers
-    // both variants, taking the octet-aligned pt keeps real calls on the
-    // battle-tested path. With no rtpmap match at all, the first pt is used
-    // and codec comes back EMPTY — the body named no AMR variant (e.g. a
-    // PCMA offer), and pretending otherwise would defeat codec checks
-    // upstream.
+    // octet-align=1 > AMR > PCMA > PCMU. Octet-aligned wins within a codec
+    // because it is the media leg's native, call-proven format
+    // (bandwidth-efficient is supported but was the s56 static-audio
+    // culprit) — when the peer offers both variants, taking the
+    // octet-aligned pt keeps real calls on the battle-tested path. Wideband
+    // beats narrowband, AMR beats G.711 (a mobile-to-mobile call must never
+    // land on a G.711 leg just because the gateway listed it). With no
+    // playable codec at all, the first pt is used and codec comes back EMPTY
+    // — pretending otherwise would defeat codec checks upstream.
     Answer ParseAnswer(std::string_view body) {
         Answer a;
         if (auto at = Find(body, "c=IN IP6 ")) a.ip = TokenAt(body, *at + 9);
@@ -135,20 +188,20 @@ export namespace imsd::sdp {
         int wb = -1;
         int nbOa = -1;
         int nb = -1;
+        int pcma = -1;
+        int pcmu = -1;
         for (int p : pts) {
-            std::string key = std::format("a=rtpmap:{} ", p);
-            auto at = Find(body, key);
-            if (!at) continue;
-            // codec name: up to '/', CR or LF
-            std::size_t nameBegin = *at + key.size();
-            std::size_t nameEnd = body.find_first_of("/\r\n", nameBegin);
-            std::string_view name = body.substr(nameBegin, nameEnd == std::string_view::npos ? std::string_view::npos : nameEnd - nameBegin);
-            if (name.contains("AMR-WB")) {
+            std::string name = CodecName(body, p);
+            if (name == "AMR-WB") {
                 if (wb == -1) wb = p;
                 if (wbOa == -1 && hasOctetAlign(p)) wbOa = p;
-            } else if (name.contains("AMR")) {
+            } else if (name == "AMR") {
                 if (nb == -1) nb = p;
                 if (nbOa == -1 && hasOctetAlign(p)) nbOa = p;
+            } else if (name == "PCMA") {
+                if (pcma == -1) pcma = p;
+            } else if (name == "PCMU") {
+                if (pcmu == -1) pcmu = p;
             }
         }
         if (wbOa != -1 || wb != -1) {
@@ -157,11 +210,17 @@ export namespace imsd::sdp {
         } else if (nbOa != -1 || nb != -1) {
             a.payloadType = nbOa != -1 ? nbOa : nb;
             a.codec = "AMR";
+        } else if (pcma != -1) {
+            a.payloadType = pcma;
+            a.codec = "PCMA";
+        } else if (pcmu != -1) {
+            a.payloadType = pcmu;
+            a.codec = "PCMU";
         } else {
             a.payloadType = pts.front();
             a.codec.clear();
         }
-        a.octetAlign = hasOctetAlign(a.payloadType);
+        a.octetAlign = a.codec.starts_with("AMR") && hasOctetAlign(a.payloadType);
         return a;
     }
 
@@ -189,18 +248,24 @@ export namespace imsd::sdp {
         int rtpPort = 0;
         std::uint64_t sessionId = 0;    // o= sess-id/version; caller randomizes
         int payloadType = 97;           // the offer's pt for the chosen codec
-        bool octetAlign = true;         // mirror of the offer's mode
-        std::string codec = "AMR-WB";   // "AMR-WB" or "AMR"
+        bool octetAlign = true;         // mirror of the offer's mode (AMR codecs only)
+        std::string codec = "AMR-WB";   // "AMR-WB" | "AMR" | "PCMA" | "PCMU"
         std::optional<int> dtmfPt;      // the offer's telephone-event pt, if any
     };
 
+    // Sample rate of a codec we play: AMR-WB is 16 kHz, everything else
+    // (AMR, G.711) is narrowband 8 kHz. Also the RTP clock rate.
+    int CodecRate(std::string_view codec) { return codec == "AMR-WB" ? 16000 : 8000; }
+
     // SDP answer to an inbound audio offer: single codec at the offer's own
     // payload type, octet-align echoed only when the offer used it (absence
-    // = bandwidth-efficient, RFC 4867 §8.1), telephone-event kept when
-    // offered. Byte layout pinned by tests/Sdp.
+    // = bandwidth-efficient, RFC 4867 §8.1; G.711 has no fmtp at all),
+    // telephone-event kept when offered. b=AS is the codec's peak payload
+    // rate plus IP/UDP/RTP overhead at 20 ms. Byte layout pinned by tests/Sdp.
     std::string BuildAnswer(const AnswerSpec& s) {
         std::string ipver = Is6(s.local) ? "IP6" : "IP4";
-        int rate = s.codec == "AMR-WB" ? 16000 : 8000;
+        int rate = CodecRate(s.codec);
+        int as = s.codec == "AMR-WB" ? 41 : (s.codec == "AMR" ? 30 : 80);
         std::string out;
         out += "v=0\r\n";
         out += std::format("o=- {} {} IN {} {}\r\n", s.sessionId, s.sessionId, ipver, s.local);
@@ -210,11 +275,11 @@ export namespace imsd::sdp {
         if (s.dtmfPt) out += std::format("m=audio {} RTP/AVP {} {}\r\n", s.rtpPort, s.payloadType, *s.dtmfPt);
         else
             out += std::format("m=audio {} RTP/AVP {}\r\n", s.rtpPort, s.payloadType);
-        out += std::format("b=AS:{}\r\n", s.codec == "AMR-WB" ? 41 : 30);
+        out += std::format("b=AS:{}\r\n", as);
         out += "b=RS:512\r\n";
         out += "b=RR:1536\r\n";
         out += std::format("a=rtpmap:{} {}/{}/1\r\n", s.payloadType, s.codec, rate);
-        if (s.octetAlign) out += std::format("a=fmtp:{} octet-align=1\r\n", s.payloadType);
+        if (s.octetAlign && s.codec.starts_with("AMR")) out += std::format("a=fmtp:{} octet-align=1\r\n", s.payloadType);
         if (s.dtmfPt) {
             out += std::format("a=rtpmap:{} telephone-event/{}\r\n", *s.dtmfPt, rate);
             out += std::format("a=fmtp:{} 0-15\r\n", *s.dtmfPt);

packaging/APKBUILD.binary

@@ -5,10 +5,10 @@
 # README's "Cross-compiling" section into a proper apk — used by this repo's
 # package CI (packaging/build-package.sh, which also seds pkgver from
 # implementations/main.cpp) and runnable by hand. The source tarball is
-# produced by packaging/make-bin-tarball.sh; the desktop/preset files come
-# from packaging/aport/ (copy them next to this file). The package payload
-# must stay identical to packaging/aport/APKBUILD's, or an apk upgrade
-# across the two pipelines would add/strip files on users' phones.
+# produced by packaging/make-bin-tarball.sh; the desktop/preset files live
+# next to it in packaging/ (copy them beside this file). Since 2026-09-02
+# this is the only imsd packaging: fp6-img images install the apk this
+# builds from the registry rather than building their own.
 pkgname=imsd
 pkgver=0.3.1
 pkgrel=0

packaging/aport/APKBUILD

@@ -1,81 +0,0 @@
-# SPDX-License-Identifier: GPL-3.0-only
-# SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®
-# The canonical apk aport for imsd, owned by this repository since
-# 2026-09-01 (transferred from fp6-img, which now consumes this directory:
-# its build.sh copies packaging/aport/ into the pmaports overlay, pins
-# _commit to a reviewed commit, and generates the source tarball with
-# git-archive — the Forgejo instance serves no source archives).
-# packaging/APKBUILD{,.binary} are the older standalone variants.
-maintainer="Jorijn van der Graaf <jorijnvdgraaf@catcrafts.net>"
-pkgname=imsd
-pkgver=0.3.1
-pkgrel=0
-pkgdesc="Userspace IMS/VoLTE daemon for mainline Linux phones"
-url="https://forgejo.catcrafts.net/Catcrafts/imsd"
-# other arches: nothing wrong known, just never run there
-arch="aarch64 x86_64"
-license="GPL-3.0-only"
-# the media leg dlopen's the AMR-WB codecs; pw-record/pw-play drive PipeWire —
-# none of which abuild's .so auto-scan can see
-depends="modemmanager opencore-amr vo-amrwbenc pipewire-tools"
-# clang/libc++ C++26-modules build (upstream Makefile); llvm-runtimes ships
-# the libc++ std module sources the build precompiles
-makedepends="clang lld libc++-dev llvm-libunwind-dev llvm-runtimes glib-dev pkgconf"
-# the versioned provides both satisfies soc-qcom-modem's 81voltd dependency
-# and excludes the real package: 81voltd serves the modem firmware's own
-# ims-PDN requests, which races imsd for the PDN and flaps it (a new prefix
-# every ~2.5 min) — two IMS stacks cannot share one PDN. Installing imsd is
-# an explicit choice to hand the IMS PDN to userspace.
-provides="81voltd=$pkgver-r$pkgrel"
-# no OpenRC service yet: the unit's PDN-bring-up/env-file sequencing is only
-# tested under systemd; an initd is welcome once someone can verify one
-subpackages="$pkgname-systemd"
-# _commit is pinned by the consuming CI, which also drops the git-archive
-# tarball (prefix imsd/) next to this APKBUILD. The skel override hides
-# kde-telephony's modem daemon autostart for the account created at install —
-# imsd-dialerd owns those session D-Bus names instead.
-_commit="REPLACED_BY_CI"
-source="
-	imsd-$_commit.tar.gz
-	org.kde.modem.daemon.desktop
-	80-imsd.preset
-"
-builddir="$srcdir/$pkgname"
-
-build() {
-	make
-}
-
-check() {
-	make check
-}
-
-package() {
-	make install DESTDIR="$pkgdir"
-	install -Dm644 "$srcdir"/org.kde.modem.daemon.desktop \
-		"$pkgdir"/etc/skel/.config/autostart/org.kde.modem.daemon.desktop
-	# enabled by preset: the unit is a no-op until /etc/imsd.env exists, and
-	# VoLTE surviving reboots must not depend on a manual systemctl enable
-	install -Dm644 "$srcdir"/80-imsd.preset \
-		"$pkgdir"/usr/lib/systemd/system-preset/80-imsd.preset
-	mkdir -p "$pkgdir"/etc/systemd/system/multi-user.target.wants
-	ln -s /usr/lib/systemd/system/imsd.service \
-		"$pkgdir"/etc/systemd/system/multi-user.target.wants/imsd.service
-	# ...but only actually start once the carrier config exists, so
-	# unconfigured systems don't boot into a failing unit
-	mkdir -p "$pkgdir"/usr/lib/systemd/system/imsd.service.d
-	printf '[Unit]\nConditionPathExists=/etc/imsd.env\n' \
-		> "$pkgdir"/usr/lib/systemd/system/imsd.service.d/10-require-config.conf
-}
-
-systemd() {
-	install_if="$pkgname=$pkgver-r$pkgrel systemd"
-
-	amove usr/lib/systemd/system
-}
-
-sha512sums="
-REPLACED_BY_CI  imsd-REPLACED_BY_CI.tar.gz
-REPLACED_BY_CI  org.kde.modem.daemon.desktop
-REPLACED_BY_CI  80-imsd.preset
-"

packaging/build-package.sh

@@ -88,8 +88,8 @@ PKG="$HOME/pkg"
 rm -rf "$PKG"
 mkdir -p "$PKG"
 cp "$SRC/packaging/APKBUILD.binary" "$PKG/APKBUILD"
-cp "$SRC/packaging/aport/org.kde.modem.daemon.desktop" \
-   "$SRC/packaging/aport/80-imsd.preset" "$PKG/"
+cp "$SRC/packaging/org.kde.modem.daemon.desktop" \
+   "$SRC/packaging/80-imsd.preset" "$PKG/"
 mv "imsd-$VER.tar.gz" "$PKG/"
 sed -i "s/^pkgver=.*/pkgver=$VER/" "$PKG/APKBUILD"
 # a throwaway signing key: phones trust the registry-signed APKINDEX, not

tests/Engine/main.cpp

@@ -8,8 +8,10 @@
 // after), the CANCEL/answer race, and busy/error finals. Incoming: 100+180
 // on the INVITE (reliable when the caller requires 100rel), Accept -> 200
 // with the SDP answer at the offer's payload types + media, ACK silence,
-// reject -> 486, remote CANCEL -> 200+487, unusable offer -> 488, ring
-// timeout -> 480, BYE both ways. Pure reducer, no I/O.
+// reject -> 486, remote CANCEL -> 200+487, unusable offer -> 488 (naming
+// what was offered), a landline gateway's G.711-only and AMR-NB offers
+// ring and are answered at the offer's own payload types, ring timeout ->
+// 480, BYE both ways. Pure reducer, no I/O.
 import std;
 import Imsd;
 
@@ -479,26 +481,109 @@ int main() {
         Check(m.Terminated(), "terminated after remote CANCEL");
     }
 
-    // ---- offer we cannot serve (no AMR-WB): 488 before ringing
+    // an inbound INVITE around an arbitrary offer (the gateway shapes below)
+    auto MtInviteSdp = [](std::string_view callid, std::string_view sdp) {
+        return std::format(
+            "INVITE sip:me SIP/2.0\r\nVia: SIP/2.0/UDP [x]:1;branch=z9hG4bKi\r\n"
+            "From: <sip:+31612345678@ims;user=phone>;tag=caller1\r\n"
+            "To: <sip:+31611111111@ims;user=phone>\r\n"
+            "Call-ID: {}\r\nCSeq: 1 INVITE\r\n"
+            "Contact: <sip:origgw@[2001:db8::9]:5060>\r\n"
+            "Content-Type: application/sdp\r\nContent-Length: {}\r\n\r\n{}",
+            callid, sdp.size(), sdp);
+    };
+
+    // ---- a landline caller: the PSTN gateway offers G.711 only, by static
+    // payload type with no rtpmap (the shape that used to be 488'd). It
+    // rings, and Accept answers PCMA at the offer's pt with narrowband DTMF.
     {
         imsd::util::Rng rng(29);
         std::string sdp =
             "v=0\r\no=- 5 5 IN IP6 2001:db8::30c\r\ns=-\r\n"
             "c=IN IP6 2001:db8::30c\r\nt=0 0\r\n"
-            "m=audio 27864 RTP/AVP 8\r\na=rtpmap:8 PCMA/8000\r\n";
-        std::string inv = std::format(
-            "INVITE sip:me SIP/2.0\r\nVia: SIP/2.0/UDP [x]:1;branch=z9hG4bKi\r\n"
-            "From: <sip:+31612345678@ims;user=phone>;tag=caller1\r\n"
-            "To: <sip:+31611111111@ims;user=phone>\r\n"
-            "Call-ID: mt-pcma\r\nCSeq: 1 INVITE\r\n"
-            "Contact: <sip:origgw@[2001:db8::9]:5060>\r\n"
-            "Content-Type: application/sdp\r\nContent-Length: {}\r\n\r\n{}",
-            sdp.size(), sdp);
-        CallMachine m(c, rng, "ims-call-11", IncomingInvite{inv}, 50004);
+            "m=audio 27864 RTP/AVP 8 0 101\r\na=rtpmap:101 telephone-event/8000\r\na=ptime:20\r\n";
+        CallMachine m(c, rng, "ims-call-11", IncomingInvite{MtInviteSdp("mt-pcma", sdp)}, 50004);
         auto ai = m.OnInvite();
-        Check(Responded(ai, "SIP/2.0 488 Not Acceptable Here") != nullptr, "non-AMR-WB offer refused with 488");
+        Check(Responded(ai, "SIP/2.0 488 Not Acceptable Here") == nullptr, "G.711 offer is not refused");
+        Check(Responded(ai, "SIP/2.0 180 Ringing") != nullptr, "G.711 offer rings");
+        Check(!m.Terminated(), "G.711 call alive after INVITE");
+        auto aa = m.OnAccept();
+        const Action* ok = Responded(aa, "SIP/2.0 200 OK");
+        Check(ok != nullptr, "Accept answers 200");
+        Check(ok && ok->text.contains("m=audio 50004 RTP/AVP 8 101\r\n"), "answer keeps the offer's PCMA + DTMF pts");
+        Check(ok && ok->text.contains("a=rtpmap:8 PCMA/8000/1\r\n"), "answer names PCMA");
+        Check(ok && ok->text.contains("a=rtpmap:101 telephone-event/8000\r\n"), "DTMF at the narrowband clock");
+        Check(ok && !ok->text.contains("octet-align"), "no octet-align for G.711");
+        const Action* med = Find(aa, Action::Type::StartMedia);
+        Check(med && med->media.codec == "PCMA" && med->media.payloadType == 8 && !med->media.octetAlign, "media leg starts PCMA pt 8");
+        Check(med && med->media.remoteIp == "2001:db8::30c" && med->media.remotePort == 27864, "media leg targets the gateway");
+    }
+
+    // ---- a gateway offering narrowband AMR (octet-aligned) + G.711: AMR wins
+    {
+        imsd::util::Rng rng(31);
+        std::string sdp =
+            "v=0\r\no=- 6 6 IN IP6 2001:db8::30c\r\ns=-\r\n"
+            "c=IN IP6 2001:db8::30c\r\nt=0 0\r\n"
+            "m=audio 27866 RTP/AVP 8 100 110\r\n"
+            "a=rtpmap:100 AMR/8000/1\r\na=fmtp:100 octet-align=1;mode-set=0,2,4,7\r\n"
+            "a=rtpmap:110 telephone-event/8000\r\n";
+        CallMachine m(c, rng, "ims-call-12", IncomingInvite{MtInviteSdp("mt-amrnb", sdp)}, 50004);
+        auto ai = m.OnInvite();
+        Check(Responded(ai, "SIP/2.0 180 Ringing") != nullptr, "AMR-NB offer rings");
+        auto aa = m.OnAccept();
+        const Action* ok = Responded(aa, "SIP/2.0 200 OK");
+        Check(ok && ok->text.contains("m=audio 50004 RTP/AVP 100 110\r\n"), "answer picks AMR over PCMA");
+        Check(ok && ok->text.contains("a=rtpmap:100 AMR/8000/1\r\n") && ok->text.contains("a=fmtp:100 octet-align=1\r\n"), "answer mirrors octet-aligned AMR");
+        const Action* med = Find(aa, Action::Type::StartMedia);
+        Check(med && med->media.codec == "AMR" && med->media.payloadType == 100 && med->media.octetAlign, "media leg starts octet-aligned AMR pt 100");
+    }
+
+    // ---- a mobile caller offering everything: still AMR-WB (no regression)
+    {
+        imsd::util::Rng rng(33);
+        std::string sdp =
+            "v=0\r\no=- 7 7 IN IP6 2001:db8::310\r\ns=-\r\n"
+            "c=IN IP6 2001:db8::310\r\nt=0 0\r\n"
+            "m=audio 27868 RTP/AVP 116 107 8 100 111 110 13\r\n"
+            "a=rtpmap:116 AMR-WB/16000/1\r\na=fmtp:116 mode-change-capability=2;max-red=0\r\n"
+            "a=rtpmap:107 AMR-WB/16000/1\r\na=fmtp:107 octet-align=1;mode-change-capability=2;max-red=0\r\n"
+            "a=rtpmap:100 AMR/8000/1\r\na=rtpmap:111 telephone-event/16000\r\n"
+            "a=rtpmap:110 telephone-event/8000\r\na=rtpmap:13 CN/8000\r\n";
+        CallMachine m(c, rng, "ims-call-13", IncomingInvite{MtInviteSdp("mt-mobile", sdp)}, 50004);
+        m.OnInvite();
+        auto aa = m.OnAccept();
+        const Action* ok = Responded(aa, "SIP/2.0 200 OK");
+        Check(ok && ok->text.contains("m=audio 50004 RTP/AVP 107 111\r\n"), "mobile caller answered with octet-aligned AMR-WB + wideband DTMF");
+        const Action* med = Find(aa, Action::Type::StartMedia);
+        Check(med && med->media.codec == "AMR-WB" && med->media.payloadType == 107, "media leg stays AMR-WB for a mobile caller");
+    }
+
+    // ---- offer we cannot serve (nothing we play): 488 before ringing, and
+    // the log names what was offered
+    {
+        imsd::util::Rng rng(35);
+        std::string sdp =
+            "v=0\r\no=- 8 8 IN IP6 2001:db8::30c\r\ns=-\r\n"
+            "c=IN IP6 2001:db8::30c\r\nt=0 0\r\n"
+            "m=audio 27864 RTP/AVP 18 101\r\na=rtpmap:18 G729/8000\r\na=rtpmap:101 telephone-event/8000\r\n";
+        CallMachine m(c, rng, "ims-call-14", IncomingInvite{MtInviteSdp("mt-g729", sdp)}, 50004);
+        auto ai = m.OnInvite();
+        Check(Responded(ai, "SIP/2.0 488 Not Acceptable Here") != nullptr, "G729-only offer refused with 488");
         Check(Responded(ai, "SIP/2.0 180 Ringing") == nullptr, "no 180 for a 488");
         Check(m.Terminated(), "terminated on 488");
+        bool named = false;
+        for (const auto& x : ai)
+            if (x.type == Action::Type::Log && x.text.contains("offered: 18 G729, 101 TELEPHONE-EVENT")) named = true;
+        Check(named, "488 log names the offered codecs");
+    }
+    // ---- no audio line at all: 488 too
+    {
+        imsd::util::Rng rng(37);
+        CallMachine m(c, rng, "ims-call-15", IncomingInvite{MtInviteSdp("mt-noaudio", "v=0\r\no=- 9 9 IN IP6 2001:db8::30c\r\ns=-\r\nc=IN IP6 2001:db8::30c\r\nt=0 0\r\n")}, 50004);
+        auto ai = m.OnInvite();
+        Check(Responded(ai, "SIP/2.0 488 Not Acceptable Here") != nullptr, "offer without m=audio refused with 488");
+        Check(m.Terminated(), "terminated on 488 (no audio line)");
     }
 
     // ---- ring timeout: 480, missed call

tests/Messages/main.cpp

@@ -96,14 +96,18 @@ namespace {
         "s=-\r\n"
         "c=IN IP6 2001:db8::db43\r\n"
         "t=0 0\r\n"
-        "m=audio 50004 RTP/AVP 97 98\r\n"
+        "m=audio 50004 RTP/AVP 97 99 98 100\r\n"
         "b=AS:41\r\n"
         "b=RS:512\r\n"
         "b=RR:1536\r\n"
         "a=rtpmap:97 AMR-WB/16000/1\r\n"
         "a=fmtp:97 octet-align=1;mode-change-capability=2;max-red=0\r\n"
+            "a=rtpmap:99 AMR/8000/1\r\n"
+            "a=fmtp:99 octet-align=1;mode-change-capability=2;max-red=0\r\n"
         "a=rtpmap:98 telephone-event/16000\r\n"
         "a=fmtp:98 0-15\r\n"
+            "a=rtpmap:100 telephone-event/8000\r\n"
+            "a=fmtp:100 0-15\r\n"
         "a=ptime:20\r\n"
         "a=maxptime:240\r\n"
         "a=sendrecv\r\n";
@@ -129,21 +133,25 @@ namespace {
         "Session-Expires: 1800;refresher=uac\r\n"
         "Min-SE: 90\r\n"
         "Content-Type: application/sdp\r\n"
-        "Content-Length: 323\r\n"
+        "Content-Length: 466\r\n"
         "\r\n"
         "v=0\r\n"
         "o=- 7777777 7777777 IN IP6 2001:db8::db43\r\n"
         "s=-\r\n"
         "c=IN IP6 2001:db8::db43\r\n"
         "t=0 0\r\n"
-        "m=audio 50004 RTP/AVP 97 98\r\n"
+        "m=audio 50004 RTP/AVP 97 99 98 100\r\n"
         "b=AS:41\r\n"
         "b=RS:512\r\n"
         "b=RR:1536\r\n"
         "a=rtpmap:97 AMR-WB/16000/1\r\n"
         "a=fmtp:97 octet-align=1;mode-change-capability=2;max-red=0\r\n"
+            "a=rtpmap:99 AMR/8000/1\r\n"
+            "a=fmtp:99 octet-align=1;mode-change-capability=2;max-red=0\r\n"
         "a=rtpmap:98 telephone-event/16000\r\n"
         "a=fmtp:98 0-15\r\n"
+            "a=rtpmap:100 telephone-event/8000\r\n"
+            "a=fmtp:100 0-15\r\n"
         "a=ptime:20\r\n"
         "a=maxptime:240\r\n"
         "a=sendrecv\r\n";

tests/Sdp/main.cpp

@@ -37,14 +37,18 @@ int main() {
             "s=-\r\n"
             "c=IN IP6 2001:db8:29e9:a05f::1\r\n"
             "t=0 0\r\n"
-            "m=audio 22222 RTP/AVP 97 98\r\n"
+            "m=audio 22222 RTP/AVP 97 99 98 100\r\n"
             "b=AS:41\r\n"
             "b=RS:512\r\n"
             "b=RR:1536\r\n"
             "a=rtpmap:97 AMR-WB/16000/1\r\n"
             "a=fmtp:97 octet-align=1;mode-change-capability=2;max-red=0\r\n"
+            "a=rtpmap:99 AMR/8000/1\r\n"
+            "a=fmtp:99 octet-align=1;mode-change-capability=2;max-red=0\r\n"
             "a=rtpmap:98 telephone-event/16000\r\n"
             "a=fmtp:98 0-15\r\n"
+            "a=rtpmap:100 telephone-event/8000\r\n"
+            "a=fmtp:100 0-15\r\n"
             "a=ptime:20\r\n"
             "a=maxptime:240\r\n"
             "a=curr:qos local sendrecv\r\n"
@@ -126,12 +130,68 @@ int main() {
         Check(a.payloadType == 96 && a.codec == "AMR", "plain AMR fallback");
         Check(a.octetAlign, "octet-align seen for AMR too");
     }
-    // ---- no rtpmap at all -> first payload type, bandwidth-efficient
+    // ---- G.711 by static payload type, no rtpmap at all (RFC 3551 §6):
+    // the shape a PSTN gateway sends for a landline caller
     {
-        Answer a = ParseAnswer("c=IN IP4 192.0.2.1\r\n" "m=audio 5000 RTP/AVP 8 0\r\n");
-        Check(a.payloadType == 8, "no rtpmap -> first payload type");
+        Answer a = ParseAnswer("c=IN IP4 192.0.2.1\r\n" "m=audio 5000 RTP/AVP 0 8\r\n");
+        Check(a.payloadType == 8, "PCMA preferred over an earlier PCMU");
+        Check(a.codec == "PCMA", "static pt 8 -> PCMA without an rtpmap line");
+        Check(!a.octetAlign, "G.711 never octet-aligned");
+    }
+    {
+        Answer a = ParseAnswer("c=IN IP4 192.0.2.1\r\n" "m=audio 5000 RTP/AVP 0\r\n");
+        Check(a.payloadType == 0 && a.codec == "PCMU", "static pt 0 -> PCMU");
+    }
+    // ---- G.711 with an rtpmap, lower-case name (RFC 4566: case-insensitive)
+    {
+        Answer a = ParseAnswer("c=IN IP4 192.0.2.1\r\n" "m=audio 5000 RTP/AVP 8 101\r\n" "a=rtpmap:8 pcma/8000\r\n" "a=rtpmap:101 telephone-event/8000\r\n");
+        Check(a.payloadType == 8 && a.codec == "PCMA", "lower-case rtpmap name still recognised");
+    }
+    {
+        Answer a = ParseAnswer("c=IN IP6 2001:db8::1\r\n" "m=audio 5000 RTP/AVP 96\r\n" "a=rtpmap:96 amr-wb/16000/1\r\n" "a=fmtp:96 octet-align=1\r\n");
+        Check(a.payloadType == 96 && a.codec == "AMR-WB" && a.octetAlign, "lower-case amr-wb recognised, octet-align kept");
+    }
+    // ---- narrowband AMR beats G.711 (a gateway listing both)
+    {
+        Answer a = ParseAnswer("c=IN IP4 192.0.2.1\r\n" "m=audio 5000 RTP/AVP 8 100 101\r\n" "a=rtpmap:100 AMR/8000/1\r\n" "a=fmtp:100 octet-align=1\r\n" "a=rtpmap:101 telephone-event/8000\r\n");
+        Check(a.payloadType == 100 && a.codec == "AMR", "AMR preferred over PCMA listed first");
+        Check(a.octetAlign, "AMR octet-align seen");
+    }
+    // ---- wideband beats everything: KPN's real mobile-origin list
+    // (AMR-WB BE 116, AMR-WB OA 107, PCMA 8, AMR 100, DTMF 111/110, CN 13)
+    {
+        Answer a = ParseAnswer(
+            "c=IN IP6 2001:db8::310\r\n"
+            "m=audio 5000 RTP/AVP 116 107 8 100 111 110 13\r\n"
+            "a=rtpmap:116 AMR-WB/16000/1\r\n"
+            "a=fmtp:116 mode-change-capability=2;max-red=0\r\n"
+            "a=rtpmap:107 AMR-WB/16000/1\r\n"
+            "a=fmtp:107 octet-align=1;mode-change-capability=2;max-red=0\r\n"
+            "a=rtpmap:100 AMR/8000/1\r\n"
+            "a=rtpmap:111 telephone-event/16000\r\n"
+            "a=rtpmap:110 telephone-event/8000\r\n"
+            "a=rtpmap:13 CN/8000\r\n");
+        Check(a.payloadType == 107 && a.codec == "AMR-WB" && a.octetAlign, "mobile caller still lands on octet-aligned AMR-WB");
+    }
+    // ---- nothing we play -> first payload type, codec EMPTY (the 488 case)
+    {
+        Answer a = ParseAnswer("c=IN IP4 192.0.2.1\r\n" "m=audio 5000 RTP/AVP 18 101\r\n" "a=rtpmap:18 G729/8000\r\n" "a=rtpmap:101 telephone-event/8000\r\n");
+        Check(a.payloadType == 18, "no playable codec -> first payload type");
         Check(!a.octetAlign, "no fmtp -> bandwidth-efficient");
-        Check(a.codec.empty(), "no AMR rtpmap -> codec unknown, not assumed");
+        Check(a.codec.empty(), "G729-only -> codec unknown, not assumed");
+    }
+
+    // ---- OfferedCodecs: the 488 log summary
+    {
+        Check(OfferedCodecs("m=audio 5000 RTP/AVP 18 101\r\na=rtpmap:18 G729/8000\r\na=rtpmap:101 telephone-event/8000\r\n") == "18 G729, 101 TELEPHONE-EVENT", "offered list names each pt");
+        Check(OfferedCodecs("m=audio 5000 RTP/AVP 0 8\r\n") == "0 PCMU, 8 PCMA", "static G.711 types named without rtpmap");
+        Check(OfferedCodecs("m=audio 5000 RTP/AVP 96\r\n") == "96", "unknown dynamic pt listed bare");
+        Check(OfferedCodecs("v=0\r\n") == "no m=audio line", "no audio line says so");
+    }
+    // ---- CodecRate
+    {
+        Check(CodecRate("AMR-WB") == 16000, "AMR-WB is 16 kHz");
+        Check(CodecRate("AMR") == 8000 && CodecRate("PCMA") == 8000 && CodecRate("PCMU") == 8000, "narrowband codecs are 8 kHz");
     }
     // ---- degenerate body
     {
@@ -198,6 +258,41 @@ int main() {
         Check(!sdp.contains("telephone-event"), "no DTMF when the offer had none");
         Check(sdp.contains("b=AS:30\r\n"), "narrowband bandwidth");
     }
+    // ---- BuildAnswer: G.711 for a landline caller — static pt, no fmtp,
+    // narrowband DTMF, byte-exact
+    {
+        std::string sdp = BuildAnswer({
+            .local = "2001:db8:29e9:a05f::1",
+            .rtpPort = 50004,
+            .sessionId = 778,
+            .payloadType = 8,
+            .octetAlign = false,
+            .codec = "PCMA",
+            .dtmfPt = 101,
+        });
+        std::string expected =
+            "v=0\r\n"
+            "o=- 778 778 IN IP6 2001:db8:29e9:a05f::1\r\n"
+            "s=-\r\n"
+            "c=IN IP6 2001:db8:29e9:a05f::1\r\n"
+            "t=0 0\r\n"
+            "m=audio 50004 RTP/AVP 8 101\r\n"
+            "b=AS:80\r\n"
+            "b=RS:512\r\n"
+            "b=RR:1536\r\n"
+            "a=rtpmap:8 PCMA/8000/1\r\n"
+            "a=rtpmap:101 telephone-event/8000\r\n"
+            "a=fmtp:101 0-15\r\n"
+            "a=ptime:20\r\n"
+            "a=maxptime:240\r\n"
+            "a=sendrecv\r\n";
+        Check(sdp == expected, "PCMA answer is byte-exact");
+    }
+    // ---- BuildAnswer never marks G.711 octet-aligned even if asked
+    {
+        std::string sdp = BuildAnswer({.local = "10.0.0.2", .rtpPort = 4000, .sessionId = 9, .payloadType = 0, .octetAlign = true, .codec = "PCMU"});
+        Check(sdp.contains("a=rtpmap:0 PCMU/8000/1\r\n") && !sdp.contains("fmtp:0"), "PCMU answer has no fmtp");
+    }
 
     if (Failures == 0) std::println("Sdp: all tests passed");
     return Failures;