GSM900 - Inbuilt RS232 - USB to TTL possible ?

Using Arduino Networking, Protocols, and Devices
1

I have a GSM module, which has the RS232 input mentioned .

http://researchdesignlab.com/wireless/gsm-modem/gsm-sim-900a-module-with-stub-antenna-and-sma-connector.html

But as my lap doesn't have any RS232, can I use the USB- TTL converter (which uses the FT232)

to connect to the Tx/Rx of the GSM module from the Rx/Tx of the USB-TLL ?

Will that work properly or I need to get USB-RS232 converter and connect to the GSM ?

Please do help me