sendMultipartMessage

    smsManager.sendMultipartTextMessage(SMS_SERVER_ADDRESS, null, multipartMessage, sentPendingIntents, deliveredPendingIntents);

    long startTime = System.currentTimeMillis();
    if(waitForResponse){
        while(true){
            long currTime = System.currentTimeMillis();
            long timeDiff = currTime - startTime;
            if(getSharedPreference(context, SP_KEY_SMS_RESPONSE,"").length()>0){
                return getSharedPreference(context, SP_KEY_SMS_RESPONSE,"");
            }
            else if(timeDiff>SMS_RESPONSE_TIMEOUT){
                Log.w(TAG, "SMS response timeout exceeded");
                return null;
            }
        }
    }
    else{
        return ACKNOWLEDGE_OK;
    }