We have a bunch of occurrences on our system where the agent doesn't transfer the call. There's already a bunch of instructions in the prompt, but all these calls have this request failed in common:

phone-call-control

. Our backend doesn't handle that event, so it fails with a bad request. In theory we shouldn't receive that event at all, since it's not present in the

serverMessages

property of the assistant defintion Call IDs: bd9062eb-9753-4f3c-b278-14672e441408 fb9d23d7-1660-4c85-b7a7-f6af7791c5e3 4f3372a5-f76c-4097-8fab-3ab8a898dd18 a4031e75-1b27-4856-96d1-088887452f1a

Hi @Nomadiction , You've configured "phoneCallProviderBypassEnabled" as true, which means we don't have control over phone call handling. As a result, we send a request to your server whenever actions like call transfers, hang-ups, or other decisions need to be made.

I'll check that

@Nomadiction No, it's not a new change or a new development - it was there before as well. Whenever you use phone call provider bypass enable set to true, now you are controlling the call SID with your credentials which is obviously true. The only change is you are passing the call to VAPI before it started. So now because of this, you are in charge for the transfer as well as terminating the call. That's why it was not working. As you are mentioning that ok for some more calls it still works, you can share the call as sID VAPI call sID. I will take a look and get back to you with the proper information why it did work and if there is some difference on our end definitely we will work on it.

This is one example: c48a7782-ebc7-41bb-90e0-513dd254159d I failed to responde the

phone-call-control

but the call was forwarded anyway, so it does work inconsistently

Looking at the call log, I don't see the call was forwarded successfully because Phone Call Control Server event was used. When this event is used, it's the user's job to do the transfer, and we mark the call as forwarded. I suggest you look into the Twilio call logs once and see if there was a successful call forwarding. Share the logs with us so that we can also check on our end. https://cdn.discordapp.com/attachments/1350135712024100903/1352117730941210706/Screenshot_2025-03-20_at_8.39.08_AM.png?ex=67dcd944&is=67db87c4&hm=3bcd90c9e34307257d8978953dfede3e3aa89bb3bac90d4637f2da9c53b51a0d&

The

phone-call-control

request failed but the call was still forwarded: https://cdn.discordapp.com/attachments/1350135712024100903/1352258350083211335/image.png?ex=67dd5c3a&is=67dc0aba&hm=7682890f9e854dd4082beab95bf55fcb70d08b614fe1dca7824bc986dca9d6f0&

When you set the phone call control server event, we simply make a request to your server. If you respond with success or failure, we still mark the call as Assistant Forwarded Call. Considering you have subscribed to this event or selected this event, you want to control how the call should be transferred or forwarded. That's why even a failure or success response doesn't matter; we still mark this call as Assistant Forwarded Call. In your case, as you're saying that even you are not handling this event on your side, and still calls are being forwarded for this case again. I suggest the same to share the Twilio call log so that I could take a look and understand what could have been going on here. https://cdn.discordapp.com/attachments/1350135712024100903/1352857986028277892/Screenshot_2025-03-22_at_9.44.29_AM.png?ex=67df8aae&is=67de392e&hm=ed8a7bef25af9ebc34bf5fe3ee1ccef0c597dc1329ad6c985c27d4e4d051d95b&

Well, this is quite frustrating, because your logs clearly says the phone-call-control failed, but the call was forwarded anyway. Which contradicts what you're saying: > which means we don't have control over phone call handling. But the call I shared was definitely forwarded even with the

phone-call-control

request. Here's the proof: Vapi Call ID: c48a7782-ebc7-41bb-90e0-513dd254159d Twilio Call SID: CAde4744103135ee8084a98d56eb50fe41 And the screenshot showing a child call that matches the forward phone number the agent called. https://cdn.discordapp.com/attachments/1350135712024100903/1353781229555679365/image.png?ex=67e2e685&is=67e19505&hm=37bdde10ceccf7f44a25e54ce5e97d481c4889faa12ea19992478c316b20420e&

Hey, I checked with the team. We found that you haven't responded to the phone call control server event, which marks the call as customer ended the call and instead of assistant forward the call. Try another call and respond to the server event as usual. If you don't respond, it'll wait for your response and eventually result into hang. Once it hangs, it goes to the user turn, which may lead to a silent timeout or the call being ended by the customer.