SIP Trunk Troubleshooting
When a trunk drops calls intermittently or rejects them outright, the answer is in the SIP — not in guesswork. Zypager reads the trace, finds the leg that breaks and tells you whether the fault is yours or the carrier's.
Problems solved
- Failed inbound / outbound calls
- 403 / 404 / 488 / 503 responses
- Caller ID and PAI/RPID/Diversion issues
- Registration vs IP-auth trunk confusion
- Codec and early-media mismatches
How Zypager helps
- Read the SIP trace and identify the failing transaction
- Compare what your system sends vs what the carrier expects
- Build carrier-ready escalation evidence
- Validate codecs, early media and DTMF end to end
Technical areas covered
Typical deliverables
- Written diagnosis of the failing leg
- Annotated SIP trace excerpt
- Carrier escalation summary
- Configuration recommendations
Frequently asked questions
Yes. One-way and no-audio problems are usually in the RTP media path or NAT/SDP handling rather than the signalling. With a SIP trace and the SDP from each leg, the media direction can be followed to the point where it stops.
Yes — Asterisk, FreeSWITCH, Kamailio, OpenSIPS and RTPengine. Many real systems combine them (edge proxy, media relay and application logic), and problems often live at the boundaries between them.
WebRTC-related work may be reviewed separately where it is directly connected to Asterisk, Kamailio, RTPengine or SIP troubleshooting, but it is not currently offered as a standard fixed-price service.
Reading traces is central to how Zypager works. A clear pcap, sngrep or Homer export, plus call details, is often enough to identify the failing transaction without live access.
Yes, on an hourly basis for urgent incidents — failed inbound/outbound calls, RTP/no-audio and carrier problems. Final scope and availability depend on access and complexity.
Related services
RTP / No-Audio Troubleshooting
One-way audio and no audio, separated from signalling.
SIP Capture / Homer
See every call. Search by Call-ID. Escalate with evidence.
Asterisk Consulting
Dialplan, PJSIP and ARI that are easier to debug and safer to run.
Not sure which service you need?
Send the symptoms and a call example. The right starting point becomes obvious from the trace.