# SPDX-License-Identifier: GPL-3.0-only
# SPDX-FileCopyrightText: Copyright (C) 2026 Catcrafts®
[Unit]
Description=Userspace IMS/VoLTE daemon (SIP register + calls over the ims PDN)
# needs the ims PDN (multiplexed netdev + global v6) — ims-pdn-up.sh
# creates/connects the bearer through ModemManager and configures the netdev
After=ModemManager.service network.target
Wants=ModemManager.service

[Service]
Type=simple
# bring up the ims PDN first; waits for modem + network registration,
# idempotent. worst case ~14 min (2 min modem wait + 5 min registration
# gate + connect retries), hence TimeoutStartSec
ExecStartPre=/usr/libexec/ims-pdn-up.sh
# a daemon older than 0.3.10 that an upgrade restarted inside its bring-up
# throttle wait: the wait — on another address only the verdict that its
# registration is gone — is handed over from its journal now that it has
# stopped (imsd.post-upgrade recorded the invocation in /run/imsd.handover)
ExecStartPre=-/usr/libexec/imsd-handover.sh
TimeoutStartSec=900
# /run/imsd.env: written by ims-pdn-up.sh (DEV= the connected ims netdev,
# LOCAL= the PDN address ModemManager assigned to it, PCSCF_DISCOVERED= the
# P-CSCF list the network put in the PDN's PCO, read from the modem,
# PCSCF_DISCOVERY= how that list came to be: found, none, failed, skipped;
# or IMSD_IDLE=<reason> alone when the bring-up found nothing to do).
# /etc/imsd.env: admin configuration, none required where discovery finds a
# P-CSCF (AGENTS.md §10, the README); it wins over the runtime-derived values
# — PCSCF= overrides discovery.
EnvironmentFile=-/run/imsd.env
EnvironmentFile=-/etc/imsd.env
# registration state (imsreg.state) + media stats live here
StateDirectory=imsd
ExecStart=/usr/bin/imsd
# registration: resume an existing SA when possible (avoids fresh-SA
# throttles); a failed bring-up exits nonzero and systemd retries, as does
# a registered imsd whose PDN address left the netdev
Restart=on-failure
RestartSec=120
# SIGTERM: engine keeps the SA + registration state for the next resume
KillMode=mixed
TimeoutStopSec=10

[Install]
WantedBy=multi-user.target