Validate the user phone number

[vinaygopinath]

Problem

The app does not provide any feedback on the entered/shared phone number and simply invokes the messaging app, which then performs validation. This is an unnecessarily long user journey, especially if the user has made a typo.

Solution

The app should validate the entered/shared phone number and indicate whether it might be valid in the region specified by the country code.

Requirements

• Use libphonenumber to validate the entered/shared phone number
• Show a warning that the phone number may not be valid, but allow the user to "continue anyway" and open the messaging app. This leaves room for libphonenumber to be inaccurate/outdated and unaware of, for example, a new series of phone numbers in a region. True validation of a phone number is not possible, and it's only the messaging app that can provide feedback on the validity and presence of a user with the given phone number.