How is a phone number determined via bluetooth?

Question

Android

This is not even a question, but an observation that interested me.
1. Turned on bluetooth on the phone (I have Nexus5 Android 4.4.2);
2. Launched a search for devices;
3. In the list of found devices, the mac-address of another phone was first displayed, and after a few seconds it was converted into the mobile number of the found device.
What is it, a bug, a feature?

Answer 1

Most likely, the user simply gave his device the same name as the phone number. To meet :)