When you make a call using Twilio, the call audio and DTMF inputs (like pressing 1) happen over the phone call itself—Twilio cannot directly open a browser on the called phone. To “open a URL” on the user’s device, you need a different approach, such as sending an SMS with the link or using a smartphone app that listens for Twilio events.

For your current setup, to handle the key press (pressing 1), make sure your Twilio webhook correctly processes the DTMF input and responds with TwiML to redirect the call or play a message. For example, after detecting "1", you can respond with a TwiML <Redirect> or <Say> tag.

Summary:

• You can’t open a browser directly from a phone call.

• Use DTMF input to control the call flow or send an SMS with the URL.

• Make sure your Twilio webhook handles the key press correctly and returns proper TwiML instructions.