SIM900 control without serial monitor

Hi. I've successfully interfaced my arduino uno board with SIM900 gsm shield. Tested it using putty as a serial monitor and it works.
The problem is I'm using this for a project which will be stand alone. How do I send AT commands from the arduino to the shield without the use of a serial monitor.
Did a lot of research but to no avail.

I don't have a SIM900 shield, but the shield I do have has jumpers on it to select which pins on the Arduino to use for serial input. You normally want to steer clear of the hardware serial pins on an Uno (0 and 1), as they are the same ones used for the USB serial. This means you need to use the SoftwareSerial library to communicate from the Arduino to the shield via the pins you select with the jumpers.

If you use a Mega 2560, it has four hardware serial ports so you can use the standard Serial library.

You haven't posted a link to the shield you have, so it is a bit hard to say for sure.

I use the simcom sim900 module. The connection between the controller and the gsm shield works perfectly.
But I wouldn't have a serial monitor to be typing out AT commands. I want to be able run AT commands directly from code and maybe just display the response on an LCD.

You still haven't posted a link to the board you have, so from the images I can see in google there are jumpers for TX and RX locate near pins D0, D1, D2 and D3. If you have an Uno you should set the jumpers so that Rx is pin 2 and Tx is pin 3, and then use the software serial library I linked to earlier to send your AT commands and read the responses.

Software serial is only reliable up to 38,400bps, so you may need to use your external terminal program to lower the baud rate that the shield is using to this speed or lower. You will need to find the correct AT command to do that.

Okay. I see what you’re talking about.
Works now. I set the jumpers to software serial pin 7 and 8 and voila. Using softwareserial.println() works.