Agentic Warm Transfers fail intermittently, transfers fail with no verbose error information

Support Help
1

I have an intermittent issue. Sometimes my agentic warm transfer works perfectly and sometimes it just completely and immediately fails. Every single time the ai receptionist is correctly calling the tool to spawn a agentic warm transfer and getting a very non descriptive result, as a result I have no idea how to troubleshoot this intermittent error.

tool output:
{“status”:“Transfer failed due to an error.. Please inform the customer that the transfer did not go through and offer to try again or assist them directly.”}

call_cd483c18ba379916e6904f5bf86
call_abbf5b5356cc2186b022c40c058
call_4244e43a5429bd83681c7530762

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 @philip

I send these calls to the Internal team to look.

Best Regards.

4

Hello @philip

Internal logs for all three transfer agent calls show explicit SIP-layer errors at the destination: user_no_answer for +180659xxxxx (destination did not pick up within ring timeout) and SIP 603 “Network Blocked” for +143223xxxxx (carrier rejection). Successful transfers to the same +180659xxxxx number confirm the platform works correctly when the destination answers. No errors were found in any other layer (LLM, TTS, ASR). The agentic warm transfer failures are caused by the transfer destinations not answering (+180659xxxxx, intermittent no-answer) or actively blocking calls at the carrier level (+143223xxxxx, 100% SIP 603 “Network Blocked”), not by a Retell platform issue.

Thank You.