actually i dont have a complicated sketch in my arduino, it is only used in controlling the lock of the turnstile, lock and unlock, my VB program only sends a value that sets HIGH and LOW on the lock, my GSM modem which is smart bro is just used for sending sms, i have a program in vb that enables to conect on my usb modem, so as soon as the student logs in, the lock will open and the parents of the student it rcv sms, the number is save in the database together with the student's info. communicating arduino and vb is simple just by the serial port tool on vb