500 error on call transfer

Support Help
1

I got this error when my outbound agent tried to make a cold transfer using Telnyx number (SIP):

error: Error transferring call, SIP status code: 500 SIP error category: telephony_provider_unavailable Error: twirp error unknown: unexpected status from INVITE response: sip status: 500: Service Unavailable

Telnyx logs shows everything went through fine on their end. What could 500 error mean?

2

The SIP 500 error with telephony_provider_unavailable indicates the telephony provider encountered an internal server error(1). This disconnection reason means the telephony provider is unavailable or experiencing errors(1).

Troubleshooting steps:

  1. Verify your SIP trunk configuration - Double-check your configuration and ensure you imported the correct information(2). If the configuration is incorrect, delete the imported number and re-import it(2).

  2. Check your SIP endpoint format - Ensure your SIP endpoint uses the correct format with ;transport= (semicolon) rather than .transport(3). The endpoint should follow the pattern like sip:sip.retellai.com;transport=tcp(3).

  3. Review detailed call logs - The call detailed log contains the disconnection reason, SIP error code, and error message to help identify the root cause(2).

  4. Contact your telephony provider - Since the SIP 500 error indicates a server-side issue with your telephony provider, open a ticket with Telnyx to investigate the error on their end(2). Even though their logs show everything went through, the 500 status code suggests their server had trouble processing the transfer request(2).

The error specifically points to a telephony provider availability issue rather than a Retell platform issue(2).

3

Hello @Janysh

Can you share the call id for this call?

4

I’m an AI Assistant for Retell AI and can help answer questions about the platform. However, I don’t have context about a specific call you’re referring to.

To retrieve call information in Retell AI, you can use the call_id(1). The call_id is a unique identifier used to identify the call in the LLM websocket and authenticate in the audio websocket(2)(1)(3).

If you need to find a call_id, you can:

  1. Use the List Calls API to retrieve calls based on filter criteria(4)
  2. Check the response from Create Web Call or Create Phone Call, which returns the call_id(2)(3)

Could you clarify which specific call you’re asking about, or let me know how I can help you with Retell AI?