//Get the instance of TelephonyManager
final TelephonyManager tm = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);

try {
    if (tm != null) {
        Class telephonyManagerClass = Class.forName(tm.getClass().getName());

        if (telephonyManagerClass != null) {
            Method getITelephony = telephonyManagerClass.getDeclaredMethod("getITelephony");

            getITelephony.setAccessible(true);

            Object iTelephony = getITelephony.invoke(tm); // Get the internal ITelephony object
            Method[] methodList = iTelephony.getClass().getMethods();
            Method handleUssdRequest = null;

            /*
             *  Somehow, the method wouldn't come up if I simply used:
             *  iTelephony.getClass().getMethod('handleUssdRequest')
            */
            for (Method _m : methodList)
                if (_m.getName().equals("handleUssdRequest")) {
                    handleUssdRequest = _m;
                    break;
                }

            /*
             * Now the real reflection magic happens
             */
            if (handleUssdRequest != null) {
                handleUssdRequest.setAccessible(true);
                handleUssdRequest.invoke(iTelephony, SubscriptionManager.getDefaultSubscriptionId(), ussdRequest, new ResultReceiver(l) {
                    @Override
                    protected void onReceiveResult(int resultCode, Bundle ussdResponse) {
                        /*
                         * Usually you should the getParcelable() response to some Parcel
                         * child class but that's not possible here, since the "UssdResponse"
                         * class isn't in the SDK so we need to
                         * reflect again to get the result of getReturnMessage() and
                         * finally return that!
                         */
                        Object p = ussdResponse.getParcelable("USSD_RESPONSE");
                        CharSequence message = "";
                        String request = "";

                        if (p != null) {
                            Method getReturnMessage, getUssdRequest;

                            try {
                                getReturnMessage = p.getClass().getMethod("getReturnMessage");

                                if (getReturnMessage != null) {
                                    message = (CharSequence) getReturnMessage.invoke(p);
                                }
                            } catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException e) {
                                e.printStackTrace();
                            }

                            t.setText(message);
                        }
                    }
                });
            }
        }
    }
} catch (ClassNotFoundException | IllegalAccessException | InvocationTargetException | NoSuchMethodException e1) {
    e1.printStackTrace();
}