The user just entered his phone number on my app.
How can I verify that the phone number belongs to the mobile device at hand and not, lets say, one that his partner-in-crime holds right next to him?
How can I validate that the phone number belongs to the device?
Not sure I fully understand the use case.
What about:
- generate a code as random number in app
- send a message to the phone number with this generated code number
- ask user to tap the number in app, within let's say 2 minutes
- if OK, continue
- if fails or timeout, quit the app.
If the question really is: “is there an API to get the phone number of the current device?” then the answer is: no there isn’t, because that would be a massive privacy fail.