Hi Vapi team, I'm experiencing an issue with the endCall tool and a BYO phone number where Vapi is not sending a SIP BYE message to the telephony provider when the call is ended. Summary of the issue: The assistant correctly triggers the endCall tool during the call The call's endedReason is assistant-ended-call, confirming Vapi's side registers the end However, Vapi does not send a SIP BYE to the telephony provider The telephony provider confirmed they are not receiving a BYE from Vapi The call only physically terminates when the mobile user hangs up manually I attached an image what they recevied from the call: What I've already checked: phoneCallProviderBypassEnabled is absent (defaults to false) ✅ serverMessages does not contain phone-call-control ✅ endedReason is assistant-ended-call ✅ Telephony provider confirmed no SIP BYE is arriving from Vapi ❌ Details: Call ID: 019dbb30-d574-7000-8880-ae89a27a758f BYO Phone Number Credential ID: f220d117-7ef8-46a0-b4d5-db4393151a2f SIP Trunk Provider: BYO SIP TRUNK Can you please investigate why Vapi is not sending the SIP BYE when the endCall tool fires? Thank you! https://cdn.discordapp.com/attachments/1496929375390531594/1496929375642456104/0.png?ex=69ebab9e&is=69ea5a1e&hm=410824a91d4a7e4021a1c8982227e0a5486acfc553238641a5052cf75c3ad1e4&

From what you described and the SIP trace, the endCall tool is triggering correctly, but the SIP session is not being properly terminated at the signaling layer, which usually points to a trunk configuration or call control handling issue between Vapi and the BYO SIP provider. I will review the call flow, SIP signaling behavior, and trunk settings to identify why the BYE message is not being issued, then implement the proper fix so calls terminate automatically when the assistant ends them. I can start investigating this right away and keep you updated as I test and validate the resolution.

hey there yes i would need to fix it. The other thing is I tried the transfer call also, the agent initiated the transfer call correctly, but it didn't ring on the phone

yes I can help with both issues. Since endCall is triggering but no SIP BYE is sent, and transferCall initiates but doesn’t ring the destination phone, it likely points to SIP trunk routing / signaling config on the BYO setup rather than the assistant logic itself. I’d be happy to take a closer look privately, review the Vapi + trunk configuration, and fix both the call termination and transfer behavior so everything works correctly. If you’d like, you can hire me and send over the setup details, and I’ll get started right away.

@Sahil @Vapi Please help me out