How to show NETWORK_TYPE changes with Broadcaster Receiver and TelephonyManager?

Question

I've been trying and looking in several sites and here in SO without success to find a solution for my goal.

I was able to detect the events when network changes from WiFi, Mobile, No connection following this example using a NetworkUtil class and a Broadcaster Receiver.

My issue is that I can't find a way to detect (within de MOBILE status) when network type changes from LTE to 3G, 3G to LTE, 2G to 3G, etc.

I came up with the NetworkUtil class below but even I'm using TelephonyManager doesn't report when there is a change in NETWORK_TYPE

Someone could help me out with this issue please. Thanks in advance.

class NetworkUtil{

public static String getConnectivityStatusString(Context context) {
    String status = null;
    String mobile_status = null;

    ConnectivityManager cm = (ConnectivityManager) context
            .getSystemService(Context.CONNECTIVITY_SERVICE);

    NetworkInfo activeNetwork = cm.getActiveNetworkInfo();


    TelephonyManager mTelephonyManager = (TelephonyManager)
            context.getSystemService(Context.TELEPHONY_SERVICE);
    int networkType = mTelephonyManager.getNetworkType();
    switch (networkType) {
        case TelephonyManager.NETWORK_TYPE_GPRS:
        case TelephonyManager.NETWORK_TYPE_EDGE:
            mobile_status = "2G"; break;
        case TelephonyManager.NETWORK_TYPE_UMTS:
        case TelephonyManager.NETWORK_TYPE_HSPA:
            mobile_status = "3G"; break;
        default:
            mobile_status = "Unknown"; break;
    }


    if (activeNetwork != null) {
        if (activeNetwork.getType() == ConnectivityManager.TYPE_WIFI) {
            status = "Wifi enabled";
            return status;
        } else if (activeNetwork.getType() == ConnectivityManager.TYPE_MOBILE && mobile_status == "2G") {
            status = "2G enabled";
            return status;
        } else if (activeNetwork.getType() == ConnectivityManager.TYPE_MOBILE && mobile_status == "3G") {
            status = "3G enabled";
            return status;
        } else if (activeNetwork.getType() == ConnectivityManager.TYPE_MOBILE && mobile_status == "Unknown") {
            status = "Mobile unknown enabled";
            return status;
        }
    } else {
        status = "No internet is available";
        return status;
    }

    return status;
}

}