pstn-trunk: stop pinning the endpoint's static callerid to the DID itself

Live trace confirmed every inbound call's CALLERID(num) came back identical
to the DID that was dialed, regardless of who actually called - meaning
every restricted-tier allowed_numbers check was structurally impossible to
satisfy, since the "caller ID" Asterisk saw was never the real one.

The [pstn-trunk] endpoint had a static `callerid=<DID>` default (redundant
for outbound - the dialplan already sets CALLERID(num) on the calling
channel before Dial(), which is what actually gets presented) with no
trust_id_inbound setting. Removed the static default and added
trust_id_inbound=yes so real caller identity the provider sends
(P-Asserted-Identity/Remote-Party-ID, in addition to the From header) is
honored for inbound calls instead of falling back to the DID.

services/pstn-trunk.sh

@@ -223,6 +223,18 @@ _pstn_write_pjsip_include() {
 ; If inbound calls stop matching after a provider-side change, re-run this
 ; service to re-resolve/re-enter them, or add extra match= lines here by
 ; hand for additional known source IPs.
+;
+; No static callerid= default on the endpoint below, on purpose. Confirmed
+; live: with one set (pinned to the trunk DID, presumably meant only as a
+; belt-and-suspenders default for outbound — the outbound dialplan already
+; sets CALLERID(num) on the calling channel before Dial(), which is what
+; actually gets presented), every INBOUND call's CALLERID(num) came back
+; identical to the DID itself regardless of who really called — every
+; restricted-tier allowed_numbers check was structurally unwinnable, since
+; the caller ID Asterisk saw was never the real one. trust_id_inbound=yes
+; below instead tells Asterisk to honor identity info the provider actually
+; sends (P-Asserted-Identity/Remote-Party-ID, in addition to the From
+; header) for this trunk, so real inbound Caller-ID reaches the dialplan.
 
 [pstn-trunk]
 type=aor
@@ -247,7 +259,7 @@ allow=ulaw,alaw
 aors=pstn-trunk
 from_user=__PSTN_DID__
 from_domain=__PSTN_SERVER__
-callerid=__PSTN_DID__
+trust_id_inbound=yes
 direct_media=no
 EOF
     sed -i "s/__PSTN_SERVER__/${SERVER}/g; s/__PSTN_DID__/${DID}/g" "$FILE"