Hi! I'm experiencing severe audio distortion on all outbound calls using a Spanish Telnyx number through Vapi. The customer's voice arrives heavily distorted making Deepgram transcription fail completely. Details: Call ID: 019d76d2-7991-7dd4-b826-f9e174d1eb44 Transcriber: Deepgram nova-2, language: es Telnyx codec: G711U (PCMU) prioritized Telnyx support confirmed the issue is in the media streaming layer between Vapi and Telnyx, not on the PSTN leg. They recommend verifying that stream_bidirectional_codec is set to PCMU on Vapi's side. Has anyone experienced this with a Spanish Telnyx number? Any help appreciated!

Root cause: Vapi hardcodes PCMU on the media stream, but your Spanish Telnyx number negotiates PCMA (European standard) → codec mismatch → distortion → Deepgram fails. Fix: Migrate to Telnyx BYO SIP Trunk this is the only community confirmed resolution. → docs.vapi.ai/advanced/sip/telnyx While you migrate: Disable G722 in Telnyx and restrict to PCMU only to reduce mismatch surface. Vapi engineering is aware no user configurable codec fix exists yet on the dashboard/API side.

Hi, I can see that your current configuration is using the standard Telnyx setup. We recommend switching to the SIP–Telnyx setup for better reliability: https://docs.vapi.ai/advanced/sip/telnyx Thank you.

We are already migrating to BYO SIP Trunk as recommended. The setup is complete but outbound calls are failing. Phone Number ID: 70440630-df91-4d30-9d43-bd23dc2f160b Credential ID: a4da714a-c335-490c-8763-9793f2f42598 Error: call.in-progress.error-sip-outbound-call-failed-to-connect Call ID: 019d85b4-336f-7ee5-b60f-dedf990ee88f Telnyx logs show zero records — calls never reach Telnyx phoneCallProvider in API response returns vapi instead of byo-sip-trunk Can you check why outbound calls are not being routed through the BYO SIP trunk?

Hi, For the call 019d85b4-336f-7ee5-b60f-dedf990ee88f, I’m seeing the following error in the SIP response: > SIP/2.0 403 – Dialed number +34663586605 (Spain / ESP) is not included in the whitelisted countries: USA, CAN, COL, BRA, PAN, MEX, SLV, SGP End reason: Q.850;cause=21;text="CALL_REJECTED" Could you please check with your telephony provider for this