Guide
VoIP troubleshooting hub
Use this hub to move from the symptom to evidence. Separate signalling problems from media problems, and test one change at a time.
Choose the symptom
Phone will not register
Start with reachability, identity, and authentication.
Call returns a SIP error
Interpret the response before changing configuration.
One-way or no audio
Follow media ports, addresses, and NAT behaviour.
Audio is choppy or robotic
Check loss, jitter, congestion, and Wi-Fi airtime.
IVR does not recognise digits
Verify the DTMF method end to end.
Wi-Fi calls drop or degrade
Investigate coverage, roaming, and contention.
Fax fails over VoIP
Separate T.38, audio passthrough, and network causes.
Evidence workflow
- Record the exact time, caller, callee, direction, and symptom.
- Check registration, DNS, routing, and authentication.
- Follow SIP signalling and read the SDP offer and answer.
- Confirm RTP packets flow in both directions.
- Measure loss, jitter, delay, and queueing.
- Preserve a sanitised packet capture or log excerpt for escalation.
Related tools: VoIP tools, call quality scorer, and SIP response lookup.