Freeze one failed direction and one transaction
Record local and UTC time, call direction, account, trunk or number ID, public source, optional prefix, routing profile, number state, destination, caller identity, SIP Call-ID, first response or timeout, SDP and media symptom. Redact personal numbers and reusable credentials.
Classify the earliest divergence: wrong source, prefix duplicated or missing, portal propagation pending, number not active, preference absent, wrong destination type, provider advanced, PBX rejected, call answered without media or E911 state incomplete.
Verify the translated source before changing the trunk
Compare the packet leaving the PBX, the firewall translation and the public address stored on the Commio trunk. Confirm the optional four-digit prefix appears exactly once before the destination in the Request-URI. Preserve the first provider response and the transaction retried after the documented propagation interval.
Do not add broad address ranges or multiple transformations to hide an ownership mismatch. Change the object that first differs from the recorded handoff.
Trace the inbound number to its ordered destinations
Confirm that the number is active and assigned to the intended inbound routing preference. Record each ordered IP, DNS, PSTN or SIP URI destination, the exact INVITE attempt, response or timeout and any subsequent attempt.
A provider advance does not prove the first PBX was unreachable for the assumed reason. Pair provider-side attempt evidence with customer-edge capture and PBX logs before changing timeout or forwarding rules.
Keep caller identity and jurisdiction evidence intact
Retain P-Asserted-Identity, Remote-Party-ID and From exactly as sent because Commio documents that precedence for originating ANI and jurisdiction. Confirm which value the PBX generated, which reached Commio and the final response.
Do not rewrite identity merely to change a CDR category or bypass a rejection. Number ownership, caller authorization, emergency identity and downstream display remain separate.
Follow SDP and both media directions to the carrier edge
The technical FAQ says Commio proxies signaling but does not anchor media, so RTP may arrive directly from a carrier rather than the SIP signaling address. Preserve offer, answer, selected codec, local and remote media addresses, firewall decision and packets in both directions.
Do not open unrestricted media access as a diagnostic shortcut. Use the current account handoff and observed SDP to create the narrowest approved rule, then repeat the exact call.
Correct one owner and retest the original symptom
Change only the demonstrated source, prefix, routing profile, number assignment, destination, PBX route, identity or media boundary. Record prior and new values, approval, effective time and rollback, then repeat the same authorized call.
One successful call does not establish failover restoration, account capacity, price, availability, emergency behavior or general compatibility. No Commio account, packet, call, media stream or failover event was inspected or tested for this diagnostic.
Sources & applicability
Primary references for the technical details above. Operational examples and planning checklists are VoIP.info editorial guidance.
- Commio outbound trunks ↗
- Commio inbound routing profiles ↗
- Commio technical FAQ ↗
- Commio originating ANI and jurisdiction ↗
- Commio E911 configuration and testing ↗
- Commio number configuration ↗
- Commio porting guide and best practices ↗
- Commio elastic SIP trunking ↗
Examples require adaptation to your topology. No live PBX or hardware testing is claimed.