GSM/GPRS SIM800 not working?

I recently bought this gsm module SIM800A GSM / GPRS / Bluetooth Modem Comparable with SIM900A - I have put a sim card and it seems to be working fine meaning it connects to the network and I can call the number using another phone.
The problem is making a call or sending a text through the module. Below is one of the basic program that I am trying to use

void setup() {
// initialize serial communications at 9600 bps:

// print the serial data to GSM
Serial.print("ATD9020XXXXXX;" ); // change here to call a number using SIM800
// wait 10 seconds before the next loop
Serial.print("ATH" ); // hold the call

void loop() {

After I have uploaded the program it just says ATD9020XXXXXX; in the serial monitor and does nothing. I have checked the RX/TX pin 100 times, also I am powering the gsm module with separate power supply. No matter what I do I am not able to find the problem. Hope you can fix it.
Thank you.

It's probably not the answer you are looking for but I would ask the retailer about it. The datasheet they provide is for the chip itself, not the board.