Hi team, we’ve been running outbound campaigns for a while and they usually execute smoothly, but recently (after the latest updates) we’re seeing major reliability issues: 1. Outbound campaigns are taking hours to execute, even when the campaign only has ~10–50 numbers. It looks like calls are not progressing/starting consistently, so the overall campaign runtime becomes extremely long. (Then when checking call logs we get Call.start.error get transport) 2. Voicemail detection is not accurate. Calls that reach voicemail aren’t being detected as voicemail, so the assistant continues the flow or stays connected longer than it should. This is impacting our outbound throughput and increasing time/cost per campaign. Could you please help us understand what may be causing this, whether this is related to a recent platform-side update/change, and what the recommended fix or workaround would be? Example Call IDs: 1. Campaign Issue ID: 03c075f2-4237-4f98-83e0-4c6f3800d47f 2. Voicemail Issue ID: 019e6f8d-2417-7ff8-bb51-91fa725d3fa5 Appreciate any assistance on this, thank you! https://cdn.discordapp.com/attachments/1509676670813077554/1509676671022928083/image.png?ex=6a1a0b76&is=6a18b9f6&hm=b9e91cf61f64482ab5807d48349d5903545e0c8fb26bf1394db6cb1f7ff888c4& https://cdn.discordapp.com/attachments/1509676670813077554/1509676671391764611/image.png?ex=6a1a0b76&is=6a18b9f6&hm=1fe789ac6f6cbd3fea33c8b7f58c32901534c4966a006ceef3fd478a135c093f& https://cdn.discordapp.com/attachments/1509676670813077554/1509676671714857061/image.png?ex=6a1a0b76&is=6a18b9f6&hm=4f7b9b2315b74936ed1d8150800c012b76243878d3cb3efb1cf59563d092bcd7&

Hey Ella, I’m currently looking into this issue and will get back to you as soon as I find a solution. Thank you for your patience. Kind regards, Akash

Thank you Akash! I really appreciate it.

Hey Ella, Apologies for the delayed response. I looked into the call ID in which you have faced the voicemail detection failures, • Root cause:** On call 019e6f8d-2417-7ff8-bb51-91fa725d3fa5, your voicemail detection is set to the OpenAI provider, which uses the gpt-4o-audio-preview model. OpenAI has since retired that model, so every detection attempt on the call failed with a 404 model does not exist error. It retried 6 times and gave up without ever evaluating the audio, which is why the voicemail was never flagged and the assistant stayed on the line. - Possible Fix : Switch the assistant's voicemail detection provider from OpenAI to Vapi Could you please confirm whether you're using your own OpenAI API key for this assistant? and for the campaign issue, I would need your Org ID so I can check a few things on my end and investigate the root cause. Kind Regards, Akash Vapi Support

This looks like a post-update issue. Call.start.error / transport usually means calls aren’t being properly spawned due to concurrency or session/transport failures. Voicemail mis-detection is likely AMD threshold/model drift after recent changes. Is this happening across all routes or only specific carriers/regions? @Ella Edwards

Hi Akash, Thank you for looking into this. We already switched the voicemail detection provider from OpenAI to Vapi, but unfortunately the issue is still occurring. The call ID provided was just one example; we've seen voicemail detection failures across 50+ calls, so it doesn't appear to be limited to the retired OpenAI model issue alone. Regarding the outbound campaign ID, I'm happy to provide the Org ID. Would you prefer that I send it here, or should I share it through a private channel for security purposes? One additional observation: Based on Jarrah's suggestion, I ran another test and was able to successfully place a call using a US number. The problems we've been experiencing with campaign execution and call reliability are occurring when calling Panama numbers (using a panama number), which is something we never experienced before with Vapi. I thought this might be useful information for your investigation. Additionally, are there any known issues, recent changes, or recommended settings related to voicemail detection that we should review on our end while you investigate? Thank you, Ella

Hey Ella, Thanks for your patience. Could you please share 2-3 failed Panama call IDs along with their timestamps after the recent fix was implemented? This will help me investigate the issue further. Kind regards, Akash

Hi Akash, I’m currently stuck because I’m unable to locate the older failed Panama voicemail calls that used Vapi voicemail detection, and I also can’t generate new failed call IDs because outbound calls to Panama numbers are not going through reliably at the moment. When attempting to place outbound calls, Vapi Composer is showing intermittent 504 Gateway timeout errors from Cloudflare. At this point, this has been blocking us for about a week and we’re unable to continue with our outbound operations. Could you please let me know what else I can provide from my side so this can be investigated and resolved as soon as possible? Happy to send any logs, screenshots, Org ID, assistant ID, phone number ID, or anything else needed — I just need guidance on what would be most useful since I can’t currently generate successful/failed Panama call examples reliably.

Hey Ella, - the most likely root cause is the call transport failing specifically on the Panama route/provider path, not the voicemail logic - US calls work, panama calls fail. That strongly suggests a route/carrier/international number issue, not a general platform outage. please provide your Org ID and tell me Whether the outbound number is free Vapi or imported/Twilio, and also the screenshot of 504 Gateway timeout errors from Cloudflare. Kind Regards, Akash

Hi Akkash, the ORG ID is: 81afea39-d676-4c87-adfc-db8f0208b75d The outbound number is Twilio, for these Panama calls. I dont have a screenshotnfor this error, the composer AI said it was getitng that but maybe its lying?

Could you please share a screenshot of the Composer AI page where you saw that error?

One second

yes, what happened?

Please ignore the earlier mention of a 504 Gateway Timeout, that was from a separate API call while we were debugging and doesn’t appear to be the core issue. I've established that ’m able to place individual outbound calls to Panama (+507) successfully from Composer AI using the same assistant, but when I run the same Panama dialing via Outbound Campaigns, the campaign gets stuck and doesn’t progress through the list.

That's good. Could you please summarize the final issue for me? The previous messages have become quite stacked up. based on the TL;DR, my understanding is that outbound campaigns to Panama numbers are failing and we need to investigate that, right?

Thats correct, I cant place batch outbound calls to panama, that is the main issue, the calls arent going out.

Previously, you mentioned that you're using a Twilio number. Could you please check whether geo-permissions for Panama are enabled on your Twilio account? please check it and let me know You need to explicitly enable it: 1. Log in to your [Twilio Console](https://console.twilio.com/) 2. Go to Voice → Settings → Geo Permissions 3. Search for Panama and ensure it is checked/enabled

yes, the geo permission is enabled. Checked and tested they are because i can place individual calls

okay, can you share me the csv file ? or just let me know whether you are following the correct E.164 Format for panama

Of course https://cdn.discordapp.com/attachments/1509676670813077554/1511892304565371072/tigo_small_batch.csv?ex=6a221aef&is=6a20c96f&hm=fd2cb0b3030530589b030ec7dc2776b6613d694563fd73376cf8b702e2ca3421&

the formatting is correct

Ok good

I need some more time to review the call logs and other relevant logs to identify the root cause. Thank you for your patience, can you tell me the name of the assistant which you are using for this?

Of course, the Assistant ID is: 3eff7d65-2736-4f40-82ca-f4cad55209d6 Thank you very much for your help, I appreciate it!

Thanks for providing the ID, I'm looking into this now. It may take some time to investigate, but I'll get back to you as soon as I have an update. Thank you for your patience.

Thank you, I'll be on standby

Hey, I was reviewing the recent call logs for your assistant, Tigo, and most of them show the ended reason as customer-ended-call. If you've encountered the error "Ended: Call.start.error get transport", could you please share the corresponding Call ID? That would be very helpful for our investigation.

Where are you seeing that? Ive been able to go back live today but through the composer, the Outbound Campaign section within the platform is where the issue lies, the calls never go out, I thought you were looking into this? As for the Ended: Call.start.error get transport I have more than 30 calls like that, when I call them outside of the platform the phone does ring. Here are some examples: Call IDs: 019e940a-333e-7000-a3c5-4243b8490768 019e94be-8791-7883-996e-055e537ec486 019e94b9-4747-7000-9ff9-f07f78a2a59a 019e94c2-354a-7000-bf47-d7a14eef388f

I'm seeing that in the debug dashboard on my end. could you please confirm whether you're experiencing any concurrency related issues?

No, I usually receive an email when I've hot my limit, I havent had that for over a week

Hi, as checked this issue is coming from Twilio side due to permission issue. Adding the error message - "endedMessage":"Couldn't Create Twilio Call. Twilio Error: Account not authorized to call +50761182134. Perhaps you need to enable some international permissions: https://www.twilio.com/console/voice/calls/geo-permissions/low-risk"

Hello, as previously mentioned, our pemissions are enabled, as you can see in the screenshot. On top of that, we can call these numbers that have the error through another platform, and they ring out, but the issue persists on Vapi. https://cdn.discordapp.com/attachments/1509676670813077554/1512453763607040130/image.png?ex=6a2425d5&is=6a22d455&hm=d0e1f664a10f4c752072f29a658081856ca8511e48b0ebc04959d2dec5ed360c&

The previous call ids had an error: Twilio Error: Account not authorized to call +50760747954. Can you please share new call ids after enabling permissions, so we can check

It isnt after enabling permissions, the permissions have always been enabled. Here are some of the call ID's for 46 calls with that we attempted to make with "Ended: Call.start.error get transport" 019e9426-c130-7000-bfad-9fd4cd5bbe6b 019e9426-c10d-7000-bc19-a91e1924f07d 019e9422-8943-7000-a943-e1bdb677cbe0 019e940a-333e-7000-92ca-0f6619e39a64 019e93e0-ff94-7ffa-8c5f-950082921d2f 019e93df-a75e-7000-b0b3-2ffdd3c37c82 019e93df-8827-7000-a7cc-77ffea0a5748 019e93de-f4a4-7000-9ad6-a37426685786 https://cdn.discordapp.com/attachments/1509676670813077554/1512461283763425310/image.png?ex=6a242cd6&is=6a22db56&hm=adeb7c09b2ae34541d1e7d73cd3ff3efa5f5759763c2fb5f57bed3e8649ec9f3&

Hi, as checked for the new call ids as well. We do see the same error: "endedMessage":"Couldn't Create Twilio Call. Twilio Error: Account not authorized to call +50760747547. Perhaps you need to enable some international permissions: https://www.twilio.com/console/voice/calls/geo-permissions/low-risk" you need to check your Twilio configuration or connect with Twilio support team.

Thanks for checking, but I don’t think this explains the issue. We are able to place various calls to Panama numbers through Vapi, while other Panama numbers fail. If this were only a Twilio geo-permission issue, I would expect all Panama calls to fail, not only certain numbers. Could you please clarify why some Panama calls are completing successfully while others are returning this Twilio authorization error?

Hey, I understand your concern, but that is the error we're receiving from Twilio. Could you please: 1. Double-check your Twilio geo-permissions and verify that calls to Panama numbers are allowed. 2. Share the call IDs for the Panama numbers you mentioned where "other Panama calls are completing successfully." This will help us compare the successful and failed cases. If neither of these helps resolve the issue, you'll need to open a support ticket with Twilio. We'll provide any details required from our side to assist with the investigation. @Ella Edwards