Added a troubleshooting section

Author: stephenvapiai

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.
 </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>