private String getPhone() {
    TelephonyManager phoneMgr = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);
    if (ActivityCompat.checkSelfPermission(activity, wantPermission) != PackageManager.PERMISSION_GRANTED) {
        return "";
    }
    return phoneMgr.getLine1Number();
}

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
List<SubscriptionInfo> subscription = SubscriptionManager.from(getApplicationContext()).getActiveSubscriptionInfoList();
for (int i = 0; i < subscription.size(); i++) {
    SubscriptionInfo info = subscription.get(i);
    Log.d(TAG, "number " + info.getNumber());
    Log.d(TAG, "network name : " + info.getCarrierName());
    Log.d(TAG, "country iso " + info.getCountryIso());
}

<uses-permission android:name="android.permission.READ_PHONE_STATE"/>