How Can I allow user input for the To field on a text message action?

[ZOCO_Unlimited]

Hello, 

I have a list of locations and have created an action to share the location with a set of data using the action: External: Start a text message. 

The "To" field is mandatory, how can I set this to open a text message without the phone number filled in to be able to share the location selected with the User's Input?