Get my phone number in android

Solution 1:

From the documentation:

Returns the phone number string for line 1, for example, the MSISDN for a GSM phone. Return null if it is unavailable.

So you have done everything right, but there is no phone number stored.

If you get null, you could display something to get the user to input the phone number on his/her own.

Solution 2:

If the function you called returns null, it means your phone number is not registered in your contact list.

If instead of the phone number you just need an unique number, you may use the sim card's serial number:

    TelephonyManager telemamanger = (TelephonyManager)getSystemService(Context.TELEPHONY_SERVICE);
    String getSimSerialNumber = telemamanger.getSimSerialNumber();