PJSIP's From-header username comes exclusively from the endpoint's
static from_user — it never falls back to the channel's CALLERID(num).
With from_user unset, Asterisk fell back to its own hardcoded default
("asterisk"), which the provider doesn't recognize as an account DID
and rejected outright: every outbound call went straight to busy with
the callee never ringing.
Restore the static from_user (required for the provider to accept the
call at all) and instead relay the per-call CALLERID(num) — personal_did
or the shared DID — via send_pai/send_rpid, which populate the
P-Asserted-Identity/Remote-Party-ID headers from the live channel
Caller-ID independent of from_user. This is the standard mechanism for
presenting a per-call Caller-ID over a trunk with one fixed From user.
Claude
c53060ee89