< icy policeman 64898> We re using LiveKit s SIP integration LiveKit Community #ask-ai

<@U07FRRZH2GN> We’re using LiveKit’s SIP integrati...

miniature-nail-35141

07/09/2025, 10:09 AM

@icy-policeman-64898 We’re using LiveKit’s SIP integration and trying to implement cold call transfer using the

TransferSIPParticipant

API as described in the documentation. However, we’re facing an issue — our SIP provider (Plivo) responded that they do not support the REFER method, which seems to be required for the cold transfer to work. Do you have any suggestions or possible workarounds for handling call transfers in this case? Or is REFER mandatory for the

TransferSIPParticipant

API to function correctly? Appreciate any guidance you can provide 🙏

tall-airline-16756

07/09/2025, 10:09 AM

Thanks for reaching out, Rajadurai. I'm an AI assistant and I'm here to help. Give me a moment while I research this topic.

tall-airline-16756

07/09/2025, 10:10 AM

The REFER SIP method is mandatory for LiveKit's

TransferSIPParticipant

API to function correctly for cold call transfers. This means that if your SIP provider (like Plivo) does not support REFER, the API will not be able to perform cold transfers as designed. There are no documented workarounds within LiveKit to bypass the need for REFER in this scenario. You might consider: In summary, REFER is a required method for the

TransferSIPParticipant

API cold call transfer functionality to work correctly. For your use case, exploring provider-side options or alternative SIP trunks might be necessary. If you need detailed guidance on configuring or using the API, I can provide that too. Sources: Transferring calls | LiveKit Docs | Agents telephony integration | LiveKit Docs | Company directory phone assistant | LiveKit Docs | pkg/sip/protocol.go | Inbound calls with Twilio Voice | LiveKit Docs | livekit/livekit_sip.pb.go | cmd/lk/sip.go

miniature-nail-35141

07/09/2025, 10:16 AM

@icy-policeman-64898 okay suggest any alternative approch for achieve this

tall-airline-16756

07/09/2025, 10:17 AM

I don't have the answer you're looking for. You could also try asking your question: • in one of the other Slack channels or • to https://deepwiki.com/livekit/livekit_composite which is trained on all LiveKit source code If you find the answer, please post it here to help others!

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