### Answer I can help you with call transfer flow in Retell AI. There are two main types of transfers available: [(1) ]() [(2) ]() Agent Transfer - Transfers the conversation from one AI agent to another AI agent within Retell [(1) ]() Call Transfer - Transfers the phone call to another phone number (works during phone calls, not web calls) [(2) ]() Setting Up Call Transfer Node: 1. Add "Call Transfer" from the 'Add New Node' menu 2. Configure the transfer number in e.164 format or as a SIP URI (e.g.,

sip:user@retellai.com

) 3. Choose your transfer type: - **Cold transfer**: Call is transferred directly to destination - **Warm transfer**: AI detects if a human answered, can leave private messages, do three-way introductions - **Agentic warm transfer**: A transfer agent has a two-way conversation with the transfer target first Key Warm Transfer Settings: - On-hold music (Ringtone, Relaxing Sound, Uplifting Beats, or No Music) - Agent detection timeout (max time to wait for agent pickup) - Whisper message (private message to transfer target) - Three-way message (message heard by both caller and transfer target) - Human detection (ensures a human answered before connecting) Caller ID Configuration: You can show either the Retell agent's number or the user's number to the transfer destination What specific aspect of call transfer flow do you need help with?

​ To learn more, see the sources I considered: [[1] Agent Transfer Node](https://docs.retellai.com/build/conversation-flow/transfer-agent-node) [[2] Call Transfer Node](https://docs.retellai.com/build/conversation-flow/call-transfer-node) ​

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

### Answer Based on your call log showing "the other side did not pick up," here are the most common causes for transfer failures when you can manually call the number successfully: [(1) ]() If you're using Warm Transfer with Human Detection enabled: [(2) ]() [(3) ]() - The system may not be detecting a human successfully [(4) ]() - Possible reasons include: - The person spoke only after the detection timeout expired - The speech was too similar to an IVR or voicemail - No human was actually present (e.g., it was an IVR or voicemail) Solutions to try: 1. Adjust Agent Detection Timeout - The default timeout is 30 seconds [(2) ]() . If the clinic takes longer to answer, increase this value in your transfer settings 2. Enable Auto-Greet - When enabled, the agent will immediately say "Hello" when the transfer target picks up, which encourages a response and increases the likelihood of detecting a human 3. Switch to Agentic Warm Transfer - If human detection isn't working reliably, try Agentic Warm Transfer, which uses a transfer agent to converse with the transfer target before bridging [(4) ]() 4. Check for Telephony Issues - Call transfer is similar to placing an outbound call, and failures can occur for similar reasons [(1) ]() [(4) ]() . The SIP connection log in your call logs can help diagnose the failure reason [(1) ](

eliability/call-performance) 5. Verify Transfer Number Format - Ensure your transfer number is in e.164 format or a SIP URI in the format

sip:username@domain

[(2) ]() What type of transfer are you using (cold or warm) , and do you have human detection enabled?

​ To learn more, see the sources I considered: [[1] Debug call transfer failure](https://docs.retellai.com/reliability/call-performance) [[2] Transfer call](https://docs.retellai.com/build/single-multi-prompt/transfer-call) [[3] Warm Transfer vs Cold Transfer - The AI Advantage in Call Centers | Retell AI](https://www.retellai.com/blog/effortless-handoffs-with-retell-ais-warm-transfer-feature) [[4] Address Metric Issues](https://docs.retellai.com/ai-qa/address-metric-issues) ​

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