Inbound calls choppy

Support Help
1

Hi team,

Inbound calls to our agent have heavy micro-cuts/choppiness on the caller’s
phone, while the Retell server recording is perfectly clean — so this is the
transport leg, not audio generation.

Details:
Example call_id: call_90f87f679bd8b90b64977d76ea7

Thanks!

2

Hey @admin23 Checking with the Team.

3

Hey @admin23

Thanks for the detailed write-up and for already isolating the symptom to the transport leg — that’s the right read.

Here’s what we can confirm from our side on call_90f87f679bd8b90b64977d76ea7:

  • Signaling is clean. Inbound INVITE → 180 Ringing → 200 OK → ACK, no anomalies, no Retell-initiated teardown (caller hung up after 233s).
  • Audio generation is healthy. Per-turn TTS render times are normal (p50 ~855 ms, p95 ~1000 ms) and the underlying provider on this call uses a single streamed response per turn, so this is not the per-sentence-pacing fingerprint we sometimes see on PSTN.
  • No Retell-side pipeline warnings, no RTP issues at our edge, and no systemic pattern — 24 other inbound calls to +34910785866 over the past 14 days connected and sustained normally.

That puts the choppiness on the downlink media path beyond Retell’s edge: LiveKit SIP gateway → your Telnyx trunk → Spanish PSTN carrier → the caller’s handset. We don’t retain per-call RTP loss/jitter for that path, so to localize the bad hop we’d need:

  1. Telnyx CDR + Quality Metrics for the leg matching SIP Call-ID f72c96f7-2a03-43e0-9371-48eb9cdff29f (window 2026-06-01 13:09:39–13:13:37 UTC, +34619049338 → +34910785866). Look at MOS, jitter, and packet loss in both directions on the Telnyx leg.
  2. If the Telnyx leg looks clean and degradation appears only on the Telnyx → ES carrier hop, that’s a ticket to open with Telnyx referencing that Call-ID; they can escalate to the terminating carrier.
  3. If Telnyx shows loss inbound from us (LiveKit → Telnyx), let us know and we can pull LiveKit SIP participant stats for that room on our side.
  4. If you can reproduce the choppiness on a second caller / different mobile carrier, that confirms it’s upstream of the last-mile radio leg; if it only reproduces on one carrier, it’s likely last-mile.

Happy to dig further once the Telnyx metrics are in.

Thank You

4

Mark nailed it – basically there are too many “hops” or forwards of the call before it gets to Retell’s phone number. See if your phone provider can do SIP trunking or otherwise cut out some of the PSTN forwards.