Hello, Yesterday, I tested VAPI with custom SIP trunk, and it worked well. Today, I made some optimizations and attempted another call, but when I answered the phone, there was no audio. Additionally, I checked the VAPI logs and saw that no voice data was being sent from my device. Here is the Call ID for reference: 0b50cd28-3e4a-4679-a438-0e7335eb16ba. Our SIP trunk provider responded with the following recommendation: "Please make sure you are using the following codecs and remove OPUS if it's enabled: ulaw, alaw, g729" We tested the SIP trunk separately (without VAPI), and audio works correctly. Could you please assist in identifying and resolving the issue?

I understand the issue you're experiencing with your custom SIP trunk. Based on the information from your SIP trunk provider, it looks like you need to configure specific codecs (ulaw, alaw, g729) and remove OPUS in your VAPI setup. I've found some information about codec compatibility with VAPI, but I don't have the specific step-by-step instructions for configuring these codecs in your environment. Since this requires detailed technical configuration, I've escalated your query to our technical support team who can provide you with the exact steps needed. A support specialist will reach out to you shortly with detailed instructions on how to configure these codecs in VAPI. They'll help you resolve the audio issues you're experiencing. In the meantime, you might want to check out our [SIP configuration guide](https://vapi.notion.site/SIP-104008c8393f80feaeb7de8ca19565ed) which provides general information about setting up SIP connections with VAPI. Thanks for your patience! 👍

Hey, the team is on vacation, so you'll have to wait until Monday (US time) to get some responses.