What is the correct way of checking for mobile network available (no data connection)

Question

What is the correct way of checking if a mobile network (GSM) connection is available on Android? (>2.1) I don't want to check if there is data connection available over the mobile network just check for network availability in general. (check if phone calls over the mobile network are possible)

At the moment I am using the following check:

public static boolean checkMobileNetworkAvailable(Context context){
    TelephonyManager tm = (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);
    int networkType = tm.getNetworkType();
    return (networkType != TelephonyManager.NETWORK_TYPE_UNKNOWN);
}

But it seems that some devices always report back "NETWORK_TYPE_UNKNOWN". So the check fails all the time.

Is there a better approach of doing it?

Update:

Would the following approach be better?

    public static boolean checkMobileNetworkAvailable(Context context){
       boolean isMobileNetworkAvailable = false;
       ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
       NetworkInfo[] networks = cm.getAllNetworkInfo();
       for(int i=0;i<networks.length;i++){
        if(networks[i].getType() == ConnectivityManager.TYPE_MOBILE){
              if(networks[i].isAvailable()){
                isMobileNetworkAvailable = true;
              }
            }
        }

    return isMobileNetworkAvailable;
}

Answer 1

I used the following code to know if I'm connected to the network (no mobile data):

    public static Boolean isMobileAvailable(Context appcontext) {       
    TelephonyManager tel = (TelephonyManager) appcontext.getSystemService(Context.TELEPHONY_SERVICE);       
    return ((tel.getNetworkOperator() != null && tel.getNetworkOperator().equals("")) ? false : true);      
}

The NetworkOperator is returned only if the phone is actually registered to a network.

Answer 2

For me works fine PhoneStateListener:

private static class YourListener extends PhoneStateListener {
    @Override
    public void onServiceStateChanged(ServiceState serviceState){           
        if (serviceState.getState() == ServiceState.STATE_IN_SERVICE) {
             // connected to cellular network
        }
    }       
}

And register in TelephonyManager:

TelephonyManager tm = (TelephonyManager) context.getSystemService(Context.TELEPHONY_SERVICE);
YourListener listener = new YourListener();
tm.listen(listener, PhoneStateListener.LISTEN_SERVICE_STATE);

At registration the telephony manager invokes the onServiceChanged() method on the listener object and passes the current state.

PS: PhoneStateListener uses Handler to post result to UI thread, so you should create it in UI thread.