Live test: AMI MessageSend to a bare "pjsip:212" produced zero SIP wire
traffic (confirmed via `pjsip set logger on` during a real delivery
attempt with the target extension actively registered) -- Asterisk
never even tried reaching the registered contact, meaning the failure
was in URI resolution before anything got sent, not a rejection from
the softphone. From already carried a domain (SMS_DOMAIN); To didn't.
Testing whether that asymmetry was the actual cause.
Explicitly a live experiment, not a confirmed fix -- next test will
show whether this produces real SIP MESSAGE traffic in the logger.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JDyKC6Kdg7tofmYSmRtgww