Xamarin.Droid - 获取设备电话号码

Question

I'm currently working on a Xamarin forms project in which I need to be able to get the user's phone number from device. It figured out that it was not possible to do that on iOS and Windows Phone, but I still want to do that for Android, that's why I've found on the Internet a piece of code that should be working on Android. I'm using MVVM pattern.

In my ViewModel, I try to get the phone number this way :

   string phoneNumber = DependencyService.Get<IPhoneNumber>().GetPhoneNumber();

Which calls this method from this class :

 public class PhoneNumber : IPhoneNumber
    {
        public string GetPhoneNumber()
        {
            TelephonyManager mTelephonyMgr;    
            mTelephonyMgr = (TelephonyManager)Application.Context.GetSystemService(Context.TelephonyService);    
            return mTelephonyMgr.Line1Number;
        }
    }

When I run my app on Android Emulator for visual studio, it works, I get a phone number made up of 11 digits. But when I'm on a real device, the method returns an empty string (""). I've put the READ_PHONE_STATE permission in my AndroidManifest.xml file. Oh also, of course, my real device has a SIM card plugged in, and it has only one SIM slot.

Did I miss something ? I'll try to test it on another device as soon as I can, but it is currently not possible.

Thanks for your help !

Answer 1

So, as Emad said in a comment of my question :

I tried this long ago using native android programs and it was shown that many operators don't give this information. Especially in Iran non of the active operators do that. I've heard it's even illegal! That's why apps like Telegram and Viber ask your number.

So, after a few more research, it is indeed not possible to get the phone number for sure without asking the user.

Hope it helped !