@Override
public String getPhoneNumber() {
    TelephonyManager telephony = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);
    String phoneNumber ="";

    try {
        if (telephony.getLine1Number() != null) {
            phoneNumber = telephony.getLine1Number();
        }
        else {
            if (telephony.getSimSerialNumber() != null) {
                phoneNumber = telephony.getSimSerialNumber();
            }
        }
    }
    catch(Exception e) {
        e.printStackTrace();
    }

    return phoneNumber;
}