I'm trying to get the multiple transfer call working and I've followed all the instructions . But it seems to work only once in a while . A lot of times it will say ok i will transfer your call and just go blank , and then later I found that I have again say who i need to get transferred to when it's quiet and then to actually executes the transfercall function . I'm updated the prompt , transfer description . But I'm not able to get rid of this issue . It repeatedly happens whenever I say "transfer my call to x" it will say ok transferring your call . Nothing will happen and it will hang up . If I say x again only then the tranfer call function seems to fire. Sample call ids 1c5d9014-59b4-4dbf-ab90-e82abb9a71d0 58172d58-f5dc-45bb-84b9-322b213ede65

Thank you for reporting this issue with the multi-call transfer functionality in Vapi. To help troubleshoot this problem more effectively, I'd like to gather some additional information: 1. Could you share which SIP provider you're using for your calls (Twilio, Telnyx, etc.)? 2. Are you using a custom LLM or Vapi's default LLM for your assistant? 3. Have you checked if your system is properly configured to handle SIP REFER messages? This is often required for transferring calls [according to our documentation](https://discord.com/channels/1211482211119796234/1211483291191083018/threads/1333634755044048979). 4. Is the

phone-call-control

server event enabled on your assistant? This can sometimes interfere with Vapi's ability to handle transfers [as noted here](https://discord.com/channels/1211482211119796234/1211483291191083018/threads/1335869152535121960). 5. What region are your calls being routed through? Some users have resolved similar issues by changing their Twilio routing region to US [as mentioned here](https://discord.com/channels/1211482211119796234/1211483291191083018/threads/1339614362742165606). 6. Could you share the exact format of the

forwardingPhoneNumber

you're using? It should be in E.164 format (e.g., +15558675309). Sources: - [Troubleshooting Call Transfer Issues](https://discord.com/channels/1211482211119796234/1211483291191083018/threads/1333634755044048979) - [Phone-Call-Control Server Event Issues](https://discord.com/channels/1211482211119796234/1211483291191083018/threads/1335869152535121960) - [Twilio Routing Region Solution](https://discord.com/channels/1211482211119796234/1211483291191083018/threads/1339614362742165606) - [SIP REFER Message Handling](https://discord.com/channels/1211482211119796234/1211483291191083018/threads/1333747605628391434) - [Call Transfer Function Issues](https://discord.com/channels/1211482211119796234/1211483291191083018/threads/1338733363468697631)

Sip provider. Twilio Open ai It's routed inside the us It is in the e164 formate

Marking this ticket as Solved ✅