@hugopdvn
The best way to trigger a tool at the very beginning of a call to recognize the caller's phone number is to set up an event listener for incoming calls. This listener should be configured to execute the phone number recognition tool as soon as the call is connected.
If your Voice API platform supports it, you can implement a webhook that triggers the tool when an incoming call event is detected. The tool would then check the caller's phone number against a database or a predefined list to recognize the caller.
If you need assistance with setting up such a feature or if you have a specific tool in mind that you would like to use, please provide more details or ask support for more info on this.