Outbound calls disconnect immediately – please enable outbound and inbound calling

Support Help
1

Hi Retell team —

Outbound calls are disconnecting immediately.

• Agent is published
• Phone number is attached for inbound and outbound
• Billing is active (Pay As You Go)
• Usage is showing on invoices
• Limits and CPS are correct

Please enable full telephony (both inbound AND outbound)
and Twilio calling permissions for my workspace.

Thank you.

2

I can’t directly enable telephony permissions for your workspace—that requires support team access. However, I can help troubleshoot common outbound call issues.

If you’re using Twilio with imported numbers via SIP trunking, verify your authentication setup:(1)

Common Issues:

  1. Missing SIP Trunk Credentials - When importing a Twilio number, you need to provide either IP whitelisting or username/password authentication(2)(1)

  2. IP Whitelisting - If using IP authentication, whitelist these ranges in your Twilio SIP trunk:(3)(1)

    • 18.98.16.120/30 (All regions)
    • 143.223.88.0/21 (certain US traffic)
    • 161.115.160.0/19 (certain US traffic)

  3. Termination URI - Ensure you’ve configured the correct termination SIP URI in your Twilio trunk and provided it when importing the number to Retell(2)(1)

  4. Authentication Error - A “telephony permission denied” error typically means missing username/password credentials when importing the number(4)

To fix authentication issues:

When importing your Twilio number, include the SIP trunk credentials:(2)

const phoneNumberResponse = await client.phoneNumber.import({
  phone_number: '+14157774444',
  termination_uri: 'someuri.pstn.twilio.com',
  sip_trunk_auth_username: 'username',
  sip_trunk_auth_password: '123456'
});

(2)

For workspace-level permissions or billing issues, contact support:

3

Thanks for the reply.

To clarify:
• I am NOT using an imported Twilio number
• I am NOT using SIP trunking
• This is a Retell-provisioned US Twilio number

Inbound and outbound are both attached to a published agent.
Billing is active and usage is showing.
Calls disconnect immediately before reaching the agent.

This appears to require workspace-level telephony enablement.
Can a Retell staff member with admin access please enable
full telephony (both inbound and outbound) for my workspace?

Thank you.

4

I cannot enable workspace-level telephony permissions directly—that requires Retell support team access with admin privileges.

For immediate disconnection issues with Retell-provisioned numbers, check these common causes:

Verify call format:(1)

  • Ensure from_number is your valid Retell-purchased number(1)
  • Ensure to_number is in E.164 format (e.g., "+12137774445")(1)
  • Retell Telephony only supports US numbers as destinations(1)

Check API authorization:(1)

  • Verify your API key authorization is correct(1)
  • Confirm override_agent_id is valid if you’re using it(1)

Review call status:(1)

  • Check the call status and error messages in your Retell dashboard(1)

For workspace-level enablement or persistent issues, contact Retell support:

The support team can review your workspace configuration and enable any required telephony permissions that may be restricted at the account level.

5

Hello @annemariejacobsrealt
Can you share the call ID for this call that disconnects?

6

To help diagnose why your inbound call disconnects after 8-11 seconds, you’ll need to provide the call ID(1).

You can find the disconnection reason through the Retell Dashboard or by using the Get Call API endpoint(1). The call ID is a unique identifier that looks like “Jabr9TXYYJHfvl6Syypi88rdAHYHmcq6”(2).

Once you have the call ID, you can retrieve call details using:

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

(2)

The response will include a disconnection_reason field that explains why the call ended(1)(2). Common reasons for early disconnection include error_no_audio_received (no audio received from Twilio or web frontend after connection), error_llm_websocket_open (LLM websocket didn’t open), or inactivity (call terminated due to silence)(1).

If you’re experiencing issues where you don’t hear anything before the call hangs up, this could indicate an audio or websocket connection problem(3).