Does sip.retellai.com support the Opus codec for inbound SIP calls (WhatsApp Business Calling)?

Support Help
1

Hi everyone,

We’re trying to connect WhatsApp Business Calling (Meta Cloud API) to a Retell voice agent over SIP.

Our setup:

  • A WhatsApp number imported into Retell with import-phone-number, with the inbound agent assigned
  • Meta sends calls to sip.retellai.com on port 5061 over TLS
  • Media encryption set to SDES-SRTP

The problem:
The call rings and is rejected within about a second. Our inbound webhook is never called.

Meta’s SIP offer contains only the Opus codec (opus/48000/2). Retell’s custom telephony docs list only PCMU, PCMA and G.722, so we think there’s no common codec and the call is rejected.

Our regular Twilio SIP trunking into Retell works fine.

Questions:

  1. Does sip.retellai.com support Opus for inbound SIP calls?
  2. If not, can it be enabled on an account, or is it planned?
  3. Has anyone connected WhatsApp Business Calling to Retell directly over SIP? If so, how?

Thanks!

2

Hey @developer1

Thanks for the detailed information. I’ll check this with the relevant team and get back to you once I have an update. Thank you for your patience.

Best Regards.

3

Hey @developer1

sip.retellai.com currently negotiates only PCMU (G.711 µ-law), PCMA (G.711 A-law), and G.722 on inbound SIP. Opus is not in the supported codec list today, and there is no per-account flag to enable it. Reference: Connect Retell voice agents to your telephony provider

I don’t have a public roadmap commitment for native Opus on inbound SIP to share. If native Opus is important for this deployment, let me know and I can pass the request along internally so it’s tracked as a feature request.

Best Regards.

4

Hey thank you for prompt response. How long it takes for the feature request to be live and do we have to pay?

5

Hey @developer1

The team is currently looking into this request. As soon as I receive any updates, I ’ll be sure to let you know.

Best Regards.