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

**URL:** <https://community.retellai.com/t/does-sip-retellai-com-support-the-opus-codec-for-inbound-sip-calls-whatsapp-business-calling/3650>\
**Category:** Support Help\
**Tags:** general\
**Created:** [September 15, 2026, 9:23am UTC](https://community.retellai.com/t/does-sip-retellai-com-support-the-opus-codec-for-inbound-sip-calls-whatsapp-business-calling/3650 "2026-09-15T09:23:13Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![developer1](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/developer1/32/2542_2.png) [@developer1](https://community.retellai.com/u/developer1)\
**Post date:** [September 15, 2026, 9:23am UTC](https://community.retellai.com/t/does-sip-retellai-com-support-the-opus-codec-for-inbound-sip-calls-whatsapp-business-calling/3650/1 "2026-09-15T09:23:13Z")

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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!

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**Author:** ![mark1](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/mark1/32/2524_2.png) [@mark1](https://community.retellai.com/u/mark1)\
**Post date:** [September 15, 2026, 12:34pm UTC](https://community.retellai.com/t/does-sip-retellai-com-support-the-opus-codec-for-inbound-sip-calls-whatsapp-business-calling/3650/2 "2026-09-15T12:34:26Z")

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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.

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**Author:** ![mark1](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/mark1/32/2524_2.png) [@mark1](https://community.retellai.com/u/mark1)\
**Post date:** [September 15, 2026, 6:34pm UTC](https://community.retellai.com/t/does-sip-retellai-com-support-the-opus-codec-for-inbound-sip-calls-whatsapp-business-calling/3650/3 "2026-09-15T18:34:53Z")

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Hey @developer1

[sip.retellai.com](http://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](https://docs.retellai.com/deploy/custom-telephony)

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.

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<div class="post-metadata">

**Author:** ![developer1](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/developer1/32/2542_2.png) [@developer1](https://community.retellai.com/u/developer1)\
**Post date:** [September 16, 2026, 6:56am UTC](https://community.retellai.com/t/does-sip-retellai-com-support-the-opus-codec-for-inbound-sip-calls-whatsapp-business-calling/3650/4 "2026-09-16T06:56:58Z")

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

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<div class="post-metadata">

**Author:** ![mark1](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/mark1/32/2524_2.png) [@mark1](https://community.retellai.com/u/mark1)\
**Post date:** [September 16, 2026, 1:21pm UTC](https://community.retellai.com/t/does-sip-retellai-com-support-the-opus-codec-for-inbound-sip-calls-whatsapp-business-calling/3650/5 "2026-09-16T13:21:02Z")

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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.