How Did GroupMe verify my number?

Question

I am working on an iPhone application where I need the user\'s phone number. From what I\'ve read (here for instance - Programmatically get own phone number in iOS), the dev

Answer 1

What GroupMe does is use the MessageUI Framework ( http://developer.apple.com/library/ios/#DOCUMENTATION/MessageUI/Reference/MessageUI_Framework_Reference/_index.html) to send a text message to their servers.

Basically it works like this:

1. The app is turned on and calls the server.
2. The server responds with a code b2bd308eb7.
3. The app sends that code via SMS to the server.
4. The server gets the code and your phone number (from SMS) and confirms them.
5. Your phone number and app are connected!

Answer 2

They send a text message to some service that they can query with their server. So by sending the code to the server, they can verify the number,