How to get Telephone Number In Android

I want to get the telephone Number. I used this sample code..

TelephonyManager tm = (TelephonyManager)getSystemService(TELEPHONY_SERVICE)开发者_运维技巧;
String strphonenumber = tm.getLine1Number();

And I used the permission- READ_PHONE_STATE.

But its returning null.

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You will only be able to get the Number from a CDMA device.

public String returnNumber() {
     String number = null;
     String service = Context.TELEPHONY_SERVICE;
     TelephonyManager tel_manager = (TelephonyManager) getSystemService(service);
     int device_type = tel_manager.getPhoneType();

     switch (device_type) {
           case (TelephonyManager.PHONE_TYPE_CDMA):
              number = tel_manager.getLine1Number();
           break;
           default:
             //return something else
             number = "no number";
            break;
     }
     return number;
}