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Send the evidence. Get a written technical response.

Send the symptoms, call examples, SIP traces, logs or architecture notes and receive a written technical response from a senior VoIP engineer. All enquiries are handled by email.

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Problem description *

To speed up diagnosis, include at least one failed call example with date/time, direction, caller/callee numbers, SIP response code if known, Call-ID if available, and whether the problem affects signalling, audio, registration, recording or routing.

All enquiries are handled by email — written, precise and easy to review.

I will redact passwords, tokens and personal data before sending logs or traces.I agree to Zypager processing this enquiry in order to respond.

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Email keeps a precise, reviewable record of the symptoms and evidence.

Useful information to include

Affected numbers
Call direction (in / out / internal)
Time of the failed call
Call-ID (if available)
SIP trace (pcap / sngrep / Homer)
RTP symptoms (one-way / no audio)
Whether it is inbound, outbound, trunk, carrier, NAT or recording related

# example — what helps
Call-ID: 7f3a9c2e@192.0.2.10
direction: outbound
symptom: 200 OK, then one-way audio
time: 2026-06-21 12:04 UTC