URGENT: Outbound Agent doesnt call properly anymore

Support Help
1

Hey,

We send leads via n8n to Retell to call leads, which worked already for 30+ Leads on an ongoing basis. Now, it says its calling leads properly which is not true (tried to call myself, nothing came through), so there seems to be a problem with the SIP Trunking (maybe?). As I said it already worked for lots of leads and just stopped working without any changes.

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2

Based on your description of calls showing as initiated but not actually connecting, this sounds like a SIP trunking configuration issue. Here are the most common causes when calls suddenly stop working:

Common SIP Trunking Issues:

  1. Termination URI or Authentication Problems(1) - If you’re using elastic SIP trunking, verify your termination SIP URI is correct and that any username/password credentials are still valid(1).

  2. Telephony Provider Configuration Changes(2) - Check your SIP trunk settings in your telephony provider (Twilio, Telnyx, Vonage, etc.). Even without changes on your end, providers can update configurations(2).

  3. Origination Settings(1) - For inbound calls, ensure your origination SIP URI is still set to sip:sip.retellai.com(1).

  4. IP Whitelisting(1) - If your provider requires IP whitelisting, confirm these IP blocks are allowed: 18.98.16.120/30 (all regions), 143.223.88.0/21 (certain US traffic), 161.115.160.0/19 (certain US traffic)(1).

Troubleshooting Steps:

For outbound calls not connecting(2):

  • Check your termination setting in your SIP trunking provider(2)
  • Verify you provided the right termination URL to Retell(2)
  • Review logs in your telephony provider(2)

For inbound calls not connecting(2):

  • Check your origination setting in your SIP trunking provider(2)
  • Review logs in your telephony provider(2)

Since this worked previously and stopped without changes on your end, I’d recommend checking with your telephony provider first to see if they made any infrastructure updates(3).

For immediate assistance with SIP trunking issues, you can:

3

Hello @Philipp_Bruckes

Can you share the call id?
and does this happens for every call or only some calls?

4

Call ID: call_cd4b7277c157420a30aeff9df41

It happens when I try to call myself (german number) and it also happened for three leads (all uk based) which came through independently.

@Omar_Ashraf

5

Based on the call ID you provided (call_cd4b7277c157420a30aeff9df41), I can help you investigate this issue. The fact that it’s affecting both German and UK numbers suggests a broader telephony routing problem.

Checking Call Details:

You can retrieve detailed information about this specific call using the Retell API(1):

import Retell from 'retell-sdk';
const client = new Retell({
 apiKey: 'YOUR_RETELL_API_KEY',
});
const callResponse = await client.call.retrieve('call_cd4b7277c157420a30aeff9df41');

(1)

Key Fields to Check:

When you retrieve the call details, look specifically at(1):

  1. call_status - Should show if the call is registered, ongoing, ended, or error(1)

  2. disconnection_reason - This will tell you exactly why the call didn’t connect. Common reasons include(1):

    • dial_busy - Number was busy(1)
    • dial_failed - Call failed to connect(1)
    • dial_no_answer - No answer from recipient(1)
    • invalid_destination - Number format or routing issue(1)
    • telephony_provider_permission_denied - Provider blocked the call(1)
    • telephony_provider_unavailable - Provider service issue(1)
    • sip_routing_error - SIP configuration problem(1)
    • marked_as_spam - Call was flagged as spam(1)

  3. public_log_url - Contains detailed debugging information about the call attempt(1)

International Calling Considerations:

Since you’re calling German and UK numbers, verify(1):

  • Your from_number is properly formatted in E.164 format (e.g., +14157774444)(1)
  • Your to_number is in E.164 format (e.g., +4912345678 for Germany, +4412345678 for UK)(1)
  • Your telephony provider supports international calling to these destinations(1)

The disconnection_reason field will be the most revealing - it will tell you exactly what’s preventing these calls from connecting(1).

**

6

Can you share the pcap file for these calls.