Based on your call logs, you’re experiencing agentic warm transfer failures with the error “Transfer failed due to an error.” The transfers are failing after approximately 16-22 seconds, which is shorter than your configured agentDetectionTimeoutMs of 30,000ms and transferTimeoutMs of 101,000ms.(1)
Your configuration shows:
- Transfer type: agentic_warm_transfer
- Agent Detection Timeout: 30,000ms (30 seconds)
- Transfer Timeout: 101,000ms (101 seconds)
- On-hold music: ringtone
- Extension: 20 (for Begoña), 22 (for Asun)
The logs indicate the transfer agent call starts successfully, but then fails before the configured timeouts are reached. This pattern is similar to issues reported in the community where warm transfers fail prematurely despite longer configured timeouts.(2)(3)
Potential causes to investigate:
-
Extension dialing issues - Your transfers include extensions (20, 22). Ensure your telephony provider supports extension dialing in the format being sent.(1)
-
SIP trunking permissions - If you’re using custom telephony via SIP trunking (like Twilio), verify that your SIP trunk has permissions for call bridging and warm transfers.(4)
-
Caller ID override - For warm transfers using SIP DIAL, Retell sets
fromandP-Asserted-Identityheaders. Verify your telephony provider supports these for warm transfers.(1) -
Human detection - The agentic warm transfer includes automatic human detection. If detection fails within the timeout window, the transfer will fail.(1)(5)
Recommended troubleshooting steps:
- Test without extensions first to isolate whether the extension is causing the failure
- Verify your SIP provider supports the warm transfer configuration you’re using
- Check if switching to a cold transfer works to rule out provider-level issues
- Contact Retell support with your call ID for detailed investigation(2)