### Answer The message "Call connected but no human response detected" indicates you're using warm transfer with human detection enabled. [(1) ]() Here's what's happening and how to address it: ## Why This Occurs When human detection is enabled, the agent checks if a human is present after the transfer target answers. The original caller is only connected once a human is detected. If the system detects what appears to be an IVR, voicemail, or doesn't receive a human-like response within the timeout, it marks the transfer as failed. [(2) ]() Possible reasons include: - No human was actually present (e.g., it was an IVR or voicemail) - The other party spoke, but only after the detection timeout expired - The speech was too similar to an IVR or voicemail and was not recognized as human ## Recommended Settings to Adjust 1. Enable Auto-greet – When enabled, the agent will immediately say "Hello" when the transfer target picks up. This encourages a response, increasing the likelihood of detecting a human. [(1) ]() 2. Increase Agent Detection Timeout – This is the maximum time the AI agent will wait to determine whether the transfer target is a human. The default is 30 seconds. Consider increasing this value to give the recipient more time to respond. 3. Consider disabling human detection – If your transfer destination is always a human (not an IVR) , you may want to disable human detection so the caller connects immediately once the transfer target answers. 4. Check your transfer destination – Ensure the number isn't routing to an IVR system or voicemail that could be misidentified. ## If Using Custom Telephony Verify your SIP trunk configuration is

correct and that your telephony provider supports the transfer type you're using. [(2) ]() [(3) ]()

​ To learn more, see the sources I considered: [[1] Transfer call](https://docs.retellai.com/build/single-multi-prompt/transfer-call) [[2] Debug call transfer failure](https://docs.retellai.com/reliability/call-performance) [[3] (URGENT) - Call transfer tool executes but no outbound call is placed (PSTN never rings)](https://community.retellai.com/t/urgent-call-transfer-tool-executes-but-no-outbound-call-is-placed-pstn-never-rings/496) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.