​ To learn more, see the sources I considered: [[1] Transfer call](https://docs.retellai.com/build/single-multi-prompt/transfer-call) ​

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

### Answer ## How to Transfer a Phone Call 1. Add Transfer Call Tool – Click "+ Add" in the tools section and select "Transfer Call" from the dropdown menu. [(1) ]() 2. Set Transfer Destination – Configure the transfer number as either: - A number in E.164 format, or a SIP URI (e.g.,

sip:user@retellai.com

) - A dynamic variable that gets substituted at runtime 3. Update the Prompt – Add transfer conditions to your prompt, such as: "If the user is angry or frustrated, use the transfer_call tool to transfer the conversation to a human agent." 4. Choose Transfer Type – Select cold transfer or warm transfer: - **Cold transfer**: Call is transferred directly to the destination - **Warm transfer**: AI can detect if the other side is human, leave private messages, or do a three-way introduction ## Displayed Caller ID Options You can configure which caller ID shows up to the transfer destination: | Option | Description | |--------|-------------| | Retell Agent's number | The transfer destination sees the Retell agent's phone number | | User's Number | The transfer destination sees the original caller's phone number | Important notes on User's Number option: - The telephony provider must support caller ID override for this to work - For warm transfers, Retell sets

from

and

P-Asserted-Identity

headers to the user's number - For cold transfers, it uses SIP REFER, and support depends on the telephony provider - Retell Twilio numbers support showing user's number on both warm and cold transfer - Retell Telnyx numbers only support this when using SIP REFER via cold transfer - If caller ID override is not supported, the transfer will fail

​ To learn more, see the sources I considered: [[1] Transfer call](https://docs.retellai.com/build/single-multi-prompt/transfer-call) [[2] Call Transfer Node](https://docs.retellai.com/build/conversation-flow/call-transfer-node) [[3] Custom Telephony Overview](https://docs.retellai.com/deploy/custom-telephony) ​

### Answer Based on the available documentation, there is no explicit feature to "hide" the phone number of the transfer destination from the original caller during a transfer. [(1) ]() [(2) ]() The caller ID configuration options only control what the transfer destination sees (either the Retell Agent's number or the User's number) . What the original caller experiences during transfer: - For warm transfers, you can configure on-hold music that plays while they wait. - The caller would typically hear ringing or hold music, but the documentation does not describe a mechanism to mask or hide the destination number from them. If you need more control over what information is exposed during transfers, you may want to explore custom telephony integration where you have more flexibility over call routing logic. [(3) ]() Check out these potentially useful sources: [Transfer call]() , [Call Transfer Node]() , [Custom Telephony Overview]() Would you like me to try to answer this more generally based on my knowledge?

### Answer The caller ID configuration in Retell AI controls what the transfer destination (the person receiving the transferred call) sees—not what the original caller sees. [(1) ]() [(2) ]() When a person calls and the AI transfers them: - The original caller will typically hear ringing or on-hold music while waiting for the transfer to connect. - The documentation does not specify that the original caller sees or is shown the transfer destination's phone number during the transfer process. The two caller ID options available are: 1. Retell Agent's number – The transfer destination sees the Retell agent's number [(1) ]() 2. User's Number – The transfer destination sees the original caller's number Both of these options configure what appears to the transfer destination, not what the original caller experiences. [(1) ]() [(2) ]()

​ To learn more, see the sources I considered: [[1] Transfer call](https://docs.retellai.com/build/single-multi-prompt/transfer-call) [[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 ## How to Set Up Call Transfer ### For Single/Multi-Prompt Agents: Step 1: Click "+ Add" in the tools section and select "Transfer Call" from the dropdown menu. [(1) ]() Step 2: Set the transfer number to either: - A number in E.164 format, or a SIP URI (e.g.,

sip:user@retellai.com

) - A dynamic variable that gets substituted at runtime - Set the transfer number extension if needed (must be 0-9, '*', '#', e.g.,

123#

) Step 3: Update your prompt with transfer conditions, such as: "If the user is angry or frustrated, use the transfer_call tool to transfer the conversation to a human agent." Step 4: Choose transfer type: - Cold transfer – Call is transferred directly to the destination - Warm transfer – AI can detect if a human answered, leave whisper messages, or do a three-way introduction Step 5 (Optional) : Configure Caller ID – Choose whether the transfer destination sees the Retell Agent's number or the User's number. ### For Conversation Flow Agents: Use the Call Transfer Node instead. [(2) ]() If you want the agent to say something like "Let me transfer you right away" before transferring, put a conversation node (with "skip response" turned on) before the Call Transfer Node. ### Warm Transfer Settings (Optional) : - On-hold music – Audio played while caller waits [(1) ]() - Whisper message – Private message to the transfer destination before connecting - Three-way message – Message spoken to both parties once connected - Human detection – Verify a human answered before connecting the caller

​ To learn more, see the sources I considered: [[1] Transfer call](https://docs.retellai.com/build/single-multi-prompt/transfer-call) [[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.