I'm trying trying to use a Telnyx BYO SIP Trunk phone number. The inbound calls work perfectly and the VAPI assistant answeres the call. BUT when starting an outbound call from VAPI the phone rings: when answering this call, the VAPI assistant audio cannot be heard by the user and the user is not able to hear the VAPI assistant. Do you have any suggestions?

Suggestion: Check your Telnyx SIP trunk's codec settings to ensure the following codecs are enabled: OPUS, G729, G711A, and G711U. In your Telnyx dashboard, navigate to your SIP trunk's Inbound tab and verify these codecs are checked:

- OPUS: checked
- G729: checked
- G711A: checked
- G711U: checked

Disabling unsupported codecs or enabling only the recommended ones can resolve outbound call audio issues. (See the [Telnyx SIP integration documentation](https://docs.vapi.ai/advanced/sip/telnyx) for details.) Source: - [Telnyx SIP integration documentation](https://docs.vapi.ai/advanced/sip/telnyx)

That is exactly what I have already configured: https://cdn.discordapp.com/attachments/1470825433485283565/1470828569692471509/image.png?ex=698cb759&is=698b65d9&hm=48cb4e6e60f73e04c7b5b9321a63fcaa4d03d079e6f814b3010af4b47dcf7d98&

any reason u r not using Twilio, its better @

Been already using Telnyx for other things. The issue appears to be related to using TLS/SRTP. Could someone please help with setting up BYO SIP Trunk with TLS/SRTP?

@SM Sounds like SIP connects but TLS/SRTP media isn’t negotiating properly, that’s why you get silence on outbound. Try temporarily disabling SRTP or forcing G.711 to confirm audio flow, and make sure Telnyx media anchoring is enabled (not bypass). If audio works, re-enable security step by step to find the mismatch. Happy to help debug

I really appreciate if you or the support team can help! If I disable TLS/SRTP i wouldn't have the issue and already confirmed this. But my use case requires encryption. What steps would you recommend towards enabling the encryption to find the issue? So far, I have tried TLS/SRTP on port 5060 as well as 5061. I had to use the direct Telnyx gateway IP addresses. Because using sip.telnyx.com when creating the credentials in Vapi results in a "400 Bad Request". The documentation also mentions this on step 4, but it's unclear why this is... https://docs.vapi.ai/advanced/sip/telnyx

@SM texted u

flagging for our team @SM . Share your call ID so our support team can look into this quicker

here are a few call ids @Evadora (Vapi) : 019c493f-8633-7000-81c3-d48bb4cb1ade 019c48bc-2bb2-7449-84c0-e90d67914b2b 019c4844-d7d1-7115-8169-f4b399e9a153

we're looking into it - will let you know when we have an update!

here is a newer call id: 019c5935-385a-755c-9c65-3312c64c9468

hey man, I solved this issue. I went to telnyx and created a new sip connections with FQDN and added the authentication username and password. Went to vapi and created an SIP Trunk integration to connect with telnyx. Inbound and outbound call is working, but on inbound vapi cant get the number of the person who called the agent. I came here to see if the support team help with that

thanks @Dias_K @SM could you please confirm if this solution works for you?