diff --git a/fern/phone-numbers/telnyx.mdx b/fern/phone-numbers/telnyx.mdx index 743376d4a..02f6ede94 100644 --- a/fern/phone-numbers/telnyx.mdx +++ b/fern/phone-numbers/telnyx.mdx @@ -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 @@ -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. +## 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 ยต-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). + + +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. +