### Answer Based on the available sources, I don't have specific information about

book_appointment_cal

being enabled globally by default or how to disable it in favor of your custom tool. However, I can confirm the proper configuration for Subagent Nodes in Conversation Flow: Subagent Node Tool Configuration: In a Subagent Node, you attach tools/functions that the agent can use during conversation [(1) ]() . The node settings include a Tools field where you attach the tools/functions this subagent can use during the conversation . Best Practices from the documentation: - Be explicit in your node instruction and tell the agent when each tool/function should be used - Use function nodes for guaranteed execution—if a tool/function must always run at a certain point in the flow, use a function node instead - Avoid adding too many tools/functions to one subagent node Potential Issue: There was a recent report in the Discord community about function nodes not working properly in Conversation Flow, specifically on telephony/voice (though they worked fine in text chat) [(2) ]() . The Retell team acknowledged spotting an issue and was working on a fix . Recommended Actions: 1. Double-check that your custom

book_appointment

tool is properly attached in the Subagent Node's Tools settings 2. Verify your node instruction explicitly tells the agent to use

book_appointment

3. Consider using a Function Node instead of relying on the Subagent Node to call the tool, as Function Nodes guarantee execution [(1) ]() For specific troubleshooting of the

book_appointment_cal

override behavior, I recommend reaching out to Retell support direc

tly, as this appears to be a configuration issue not covered in the available documentation.

​ To learn more, see the sources I considered: [[1] Subagent Node](https://docs.retellai.com/build/conversation-flow/subagent-node) [[2] Discord message from @momsramen on 2025-07-22](https://discord.com/channels/1186424376300679209/1186462578310910112/1397031478965043312) ​

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

### Answer Based on the available documentation, I don't have specific information about global tool override behavior or how to disable

book_appointment_cal

at the agent level. However, I can provide guidance on the recommended approach based on Conversation Flow best practices: Function Node vs. Subagent Node [(1) ]() [(2) ]() The key difference is: - **Function Nodes**: Deterministic — executes on node entry [(1) ]() - **Subagent Nodes**: LLM-driven — called when the LLM decides it's appropriate Use function nodes when you want guaranteed execution every time the flow reaches that step. Use subagent nodes when the agent should decide whether and when to call a tool/function based on what the user says. Recommended Workaround Given your issue occurs specifically on telephony and you need guaranteed execution of your custom

book_appointment

tool, consider switching to a Function Node instead of a Subagent Node [(1) ]() [(2) ]() : 1. Function Nodes execute deterministically on node entry [(2) ]() 2. They support one tool per node [(1) ]() 3. They're designed for "always-execute actions" Function Node Configuration [(2) ]() When the function node has

wait for result

turned on, the agent will wait for the function to finish executing before attempting to transition to any other node, guaranteeing that when you reach the next node, the

result is already ready to be used . Historical Issue Note The Discord message you referenced from July 2025 mentions that the Retell team was investigating an issue where Conversation Flow agents stayed silent after function nodes, and a fix was deployed [(3) ]() [(4) ]() . However, this was a different issue related to message ordering. For specific troubleshooting of the

book_appointment_cal

override behavior with your agent ID, I recommend contacting Retell support directly through their support channels, as this appears to be a configuration issue not fully covered in the available documentation.

​ To learn more, see the sources I considered: [[1] Subagent Node](https://docs.retellai.com/build/conversation-flow/subagent-node) [[2] Function Node Overview](https://docs.retellai.com/build/conversation-flow/function-node) [[3] Conversation Flow agent potentially stay silent after function node](https://community.retellai.com/t/conversation-flow-agent-potentially-stay-silent-after-function-node/135) [[4] Discord message from @momsramen on 2025-07-22](https://discord.com/channels/1186424376300679209/1186462578310910112/1397031478965043312) ​

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

### Answer Hello! How can I help you with Retell AI today?

message has been deleted

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

### Answer Yes, you can access the caller's phone number during a live call using dynamic variables in Retell AI. How to Capture the Caller's Phone Number The caller's phone number is automatically available as a dynamic variable that you can reference in your conversation flow [(1) ]() . You need to set this up properly: 1. Set the dynamic variable at the conversation flow level - Add a default dynamic variable (e.g.,

user_number

) that will contain the caller's phone number 2. Pass the caller's number when initiating the call - When you create or register the call, include the caller's phone number in the

default_dynamic_variables

object 3. Reference it in your prompts - Use

{{user_number}}

(or whatever you named your variable) in your node instructions Example Configuration In your conversation flow configuration, you would include:

json
{
  "default_dynamic_variables": {
    "user_number": "+12137771234"
  }
}

Why Your Current Setup Isn't Working Based on your prompt snippet, you're correctly trying to use

{{user_number}}

, but the variable likely isn't being populated with the actual caller's phone number. The dynamic variable needs to be set when the call is initiated, not just referenced in the prompt. Recommended Solution Use a Code Node early in your conversation flow to capture and format the caller's number [(2) ]() :

javascript
// Assuming the caller's number is available in metadata
const callerNumber = metadata.from_number || metadata.caller_phone;
return { user_number: callerNumber };

Then your prompt logic will work as intended - when the user says "same number," the agent can confirm using

{{user_number}}

[(1) ]() . Alternative: Extract Dynamic Variable Node You could also use an Extract Dynamic Variable Node to capture the phone number if the user speaks it aloud, storing it as a Text variable [(3) ]() .

​ To learn more, see the sources I considered: [[1] Get Conversation Flow](https://docs.retellai.com/api-references/get-conversation-flow) [[2] Code Node](https://docs.retellai.com/build/conversation-flow/code-node) [[3] Extract Dynamic Variable Node](https://docs.retellai.com/build/conversation-flow/extract-dv-node) ​

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