Recurring call issues: busy/no answer status and AI unable to hear the user

Support Help
1

Hello,

I am experiencing issues when making calls to the number +55312391. Whenever I try to call this

I have been in contact with the number provider (Twilio), and after analyzing the case, we identified that the call request is correctly sent and reaches Twilio. However, when Twilio attempts to forward the call to your system, according to their support team, the request appears to be rejected. As a result, I am unable to complete

Twilio has provided supporting documentation confirming that the call attempt was successfully initiated but rejected by Retell. Please find the Drive link containing the Twilio log files below:

Additionally, these call records do not appear in the “call history” logs. However, we were able to retri

Record

  • Twilio ID: CAdf122216559f14c4ffe8e

  • D

  • Status:

  • Start Time:

  • Date Crea

  • Dura

  • From:

  • To: gole: ”+553123915687@sip.retellai.com”

Recor

  • Twilio ID: CAe5bf0c5cf7a1e35

  • Dir

  • Status: no a

  • Start T

  • Date Created:

  • Duration:

  • From: +5575998042725

  • To: gole: “+553123915687@sip.retellai.com”

Another issue I am currently investigating with Twilio: whenever I initiate an outbound call from +551130386944 → +5575998215082, the AI is u

  • Call ID: call_b53f63_

This issue is becoming frequent. Is this problem, where the AI cannot hear the caller, related to the provider, or is it something you have encountered in other cases? If you have seen similar scenarios, what would be the recommended approach to resolve this issue?

2

Thank you for reaching out to Retell AI Support. We’ve received your ticket and our team will respond within 8 hours.

3

Hi Retell,

Here are some resources to assist you with your Retell AI integration:

Best,
Evy AI
AI Support Agent @ Retell AI

4

I need to speak with a human, as I am currently facing some issues.

On the Discord channel, I’m unable to report a bug in the “bug-report” text channel.
Could someone please help me with this issue?:face_with_raised_eyebrow:

image
image1972Ă—1053 197 KB

5

You are routing the calls wrong, under the termination uri it shouldn’t be a phone number, you should use sip:sip.retellai.com and either use credentials or our ip cidr block.

If you experience any other issues with this let us know.

Thanks,

6

Hello, how are you? @colinproctor11 @support2
Thank you for your response.

The data previously shared corresponds to logs I retrieved from Twilio. The SIP mentioned in the message was also obtained from those logs. The URI is correctly configured, and I have just tested it with all three of my numbers, which are all working properly for inbound calls.

On Twilio, the URI is configured as shown in the attached image.

image
image279Ă—143 2.55 KB

When I call the numbers from my personal phone, all of them work correctly. However, when I initiate outbound calls, all numbers work except for the number we purchased from SĂŁo Paulo.

We conducted tests by triggering calls to all three numbers. Two of them worked as expected. However, for one specific number, the call is successfully connected, but the voice agent is unable to hear our audio.

Below are the logs of the failed attempts:

  • call_4ba8724b4f3b1043ab6af530214

  • call_8a615e25271dfa8766c8cc42f26

And here are the logs of the successful attempts (with the other two numbers):

  • call_7751034b61fa67ca06c34208206

  • call_92261807f668cabe3308329e4d4

It’s important to note that all three numbers are configured under a single SIP setup. All of them work correctly for inbound calls, but one specific number fails only for outbound calls.

7

Hello,

Inbound calls to +553123915687 being rejected
We found that the phone number is stored in our system as +5553123915687, but when Twilio sends the inbound call, it uses +553123915687 in the SIP request. These don’t match, so our system can’t find the number and the call gets rejected, which is also why these calls don’t appear in your call history.
The correct Brazilian E.164 format for this number is likely +553123915687 (country code +55, area code 31). To fix this, please delete the current phone number +5553123915687 from your Retell dashboard and re-import it as +553123915687.

Regarding the issue with the AI unable to hear the user, please provide call ID(s) where this happens.
The call_id you tried to share was incomplete:

Another issue I am currently investigating with Twilio: whenever I initiate an outbound call from +551130386944 → +5575998215082, the AI is u

  • Call ID: call_b53f63_

Regards,
Retell Support Team

8

Hello, how are you?
Thank you for your response.

Regarding the number +553123915687, I made an adjustment, tested it, and it is now working correctly. Thank you for the support.

As for the issue where the AI is unable to hear the user, this behavior occurs with the number +551130386944.

Below are some logs from the tests we performed. It is important to note that this issue happens when we initiate a call (i.e., during outbound calls). When we call the number +551130386944 from our personal phone, the AI is able to interact normally with the user.

Logs:

call_e42c626f21e04141c8887e634e1
call_20938daaf29be5695ca67149b7c

In the logs above, I used two different numbers to test the scenario, and in both cases the same issue occurred: the AI is unable to hear the user.

9

Hello,

Thank you for providing the call IDs, we will look into them and get back to you.

Regards,
Retell Support Team

1 Like
10

Hello,

Regarding the issue where AI can’t hear the user, we’ve confirmed that our system receives the call and the agent speaks, but no audio arrives from the called party. However, there are no errors on Retell’s side. This points to a media relay issue on the Twilio SIP trunk for that number.
Please open a ticket with Twilio specifically about the SIP trunk not relaying incoming audio back through the media path.

Regards,
Retell Support Team

11

Perfect, I am already in contact with the Twilio team.
Thank you for the support.