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Added a troubleshooting section for Telynx #1232

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stephenvapiai merged 2 commits into from
Sep 18, 2026
Merged

Added a troubleshooting section for Telynx #1232

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Added a troubleshooting section
stephenvapiai Sep 17, 2026
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Merge branch 'main' into docs/telnyx-audio-troubleshooting
stephenvapiai Sep 17, 2026
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21 changes: 20 additions & 1 deletion fern/phone-numbers/telnyx.mdx
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Expand Up @@ -2,7 +2,7 @@
title: Import number from Telnyx
subtitle: Import and use your Telnyx numbers with Vapi
slug: telnyx
description: Import your existing Telnyx phone numbers into Vapi and enable outbound calling, so your assistants or squads can place calls on your Telnyx numbers.
description: Import and troubleshoot your existing Telnyx phone numbers in Vapi, then enable outbound calling so your assistants or squads can use them to place calls.
---

## Overview
Expand Down Expand Up @@ -60,3 +60,22 @@ To enable outbound calling with your imported Telnyx numbers, configure your Tel
Without this configuration, outbound calling functionality will not work properly with your Telnyx numbers on the Vapi platform.
</Note>

## Troubleshooting

### Distorted caller audio on some calls outside North America

On some calls outside North America, the native Telnyx integration may receive static or garbled audio from the person on the phone. Transcripts may be empty or fragmented.

Some of these call legs use G.711 A-law (PCMA), while the native Telnyx integration currently expects G.711 µ-law (PCMU). This codec mismatch can make the phone audio unintelligible.

Try these in order:

1. Switch your transcriber to Deepgram Nova-3. It may recover transcripts on some calls, but it does not fix the underlying audio, so recordings may remain distorted.
2. Ask Telnyx support whether they can make PCMU the preferred codec for the affected phone number or connection.
3. Try a US-based Telnyx phone number. It may negotiate PCMU and avoid the mismatch, but verify the result with a test call.
4. Use a phone number from another provider, such as [Twilio](/phone-numbers/import-twilio) or Vonage.
5. If you already use a SIP trunk, route the number through it instead of the native Telnyx integration. This uses a different media path and may avoid the issue. See the [Telnyx SIP integration](/advanced/sip/telnyx).

<Note>
Browser-based web calls use a separate WebRTC media path rather than the native Telnyx media-streaming path. A successful web call does not rule out this issue on a Telnyx phone call.
</Note>
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