Maybe something less complicated can do the job like.... GPRS instead of
GSM.

Once you have established your GPRS session, you are on the Internet with an
IP address.  Then, you can initiate any IP connections to any remote site.

You will be charged by the volume of data instead of the connection time.
You can be hooked to the internet all day without exchanging any data and it
will cost you nothing.

To connect:
at+cgdcont=1,"IP","<APN>"
atdt*99#
<APN> = APN name of your provider. (Rogers in Canada is "internet.com" or
"vpn.com")

If you go on www.gsmworld.com  you can download the AT command sets of
GSM/GPRS.

If you want to develop an application and resell it, it is preferable to
develop it in GPRS as it is the first step to EDGE and 3G.  More scalable
and up to date than GSM circuit switched communications.

By the way, some carriers in north america does not support GSM circuit
switched communication so.......  THINK BIG!!!

For GSM/GPRS radios you have the choice.
- Wavecom (www.wavecom.com)
- Enfora (www.enfora.com)
- RIM (www.rim.net)
- G18 or G20 OEM Board from Motorola (www.motorola.com).
- Webtech Wireless (www.webtechwireless.com, they have integrated the G18
inside their box)
- The new Ericsson OEM board
- Bluetree Wireless (www.bluetreewireless.com), they have integrated the RIM
oem Board.

If it is for the European market, look for 900/1800 mhz frequencies
if it is for North american market, look for 850/1900 mhz frequencies.

hope this help

Dan