Hello, I am experiencing an issue with call transfers via VAPI. When a call is transferred to a SIP extension on my Yeastar PBX, it disconnects immediately. Context • Service: VAPI • PBX: Yeastar • SIP Destination: sip:24@15.236.116.208:5060 • Port: 5060 • Transfer Mode: blind-transfer • SIP Verb (default): refer Issue 1. Call starts successfully. 2. Transfer executes to sip:24@15.236.116.208:5060. 3. Call disconnects immediately. 4. Extension 24 does not ring or respond. VAPI seems to use SIP REFER, which may not be handled correctly by Yeastar. Current JSON Transfer Setup { "assistantId": "aade7cc3-e4f6-4b3f-b095-c3abc0dc83d4", "customer": { "number": "+{{1.

1

}}", "name": "{{1.

0

}}" }, "phoneNumberId": "b6f468d7-8fb8-4996-9b46-dc4002aaed87", "assistant": { "model": { "tools": [ { "type": "transferCall", "function": { "name": "transferCall", "parameters": { "properties": { "destination": { "enum": ["sip:24@15.236.116.208:5060"], "type": "string" } } } }, "destinations": [ { "type": "sip", "sipUri": "sip:24@15.236.116.208:5060", "transferPlan": { "mode": "blind-transfer", "sipVerb": "invite" } } ] } ] } } } 1. Can VAPI use SIP INVITE instead of REFER ("sipVerb": "invite") ? 2. Can "warm-transfer-say-message" be used instead of blind-transfer? 3. Can "sipVerb": "bye" work for this scenario? 4. Are there logs explaining why the transfer disconnects?

Hello brother, did you setup the SIP yourself? How did you do it? Just enquiring.

Hello ! I set this up thanks to the vapi documentation

@willinabus what documentation did you use? can you share the link?

sure here is the documentation from api.vapi.ai https://cdn.discordapp.com/attachments/1337383511329345588/1337405276424241282/api_transferuri_vapi_sip.pdf?ex=67a75339&is=67a601b9&hm=c2c3b481a9636bcaed4172e2c5357690ee84dd86895287d92ad82caf0d6192ab&

@willinabus Great! THanks for sharing

Hi there! Same issue for me for call transfer to twilio SIP domain: "Refer is only supported on SIP call legs". Can we change to or and would that help? https://cdn.discordapp.com/attachments/1337383511329345588/1337426531244441630/image.png?ex=67a76705&is=67a61585&hm=34b564b37d86f269fe7d6994b3bbd7cfcf4388e2acd1823ab9261b992bfc2192&

@willinabus can you share the call ID please.

Hi @Shubham Bajaj here is the call ID: 9e7651a2-f1fc-4fbc-b575-366fa5c5db1d

Hi sure here you have : 3ea00d07-877b-486a-9232-f353191295f7

Thanks for sharing the both call IDs it's on us, and we will soon ship it.