Hi.
Here is a piece of code I wrote for a Basic Stamp 2.
I hope it helps you to get started.

Regards
Stefan.

Code:
 =========================================================================
'
'   File...... GsmN12i.BS2
'   Purpose... Send SMS using a Nokia GSM-module
'   Author.... Stefan Johansson
'   E-mail.... xxxxxx
'   Started... 2006-11-23
'   Updated... 2006-11-23
'
'   {$STAMP BS2}
'   {$PBASIC 2.5}
'
' =========================================================================


' -----[ Program Description ]---------------------------------------------

'
' Program send a SMS using a NOKIA N12i GSM-module.
'
'
'   Ascii-codes:
' å = 134
' Å = 143
' ä = 132
' Ä = 142
' ö = 148
' Ö = 153
' Ctrl+Z = 26     (Used to send message.)
' ---------------------------


' -----[ I/O Definitions ]-------------------------------------------------
TX         PIN     7      'N12i Pin 27
RX         PIN     9      'N12i Pin 29

' -----[ Constants ]-------------------------------------------------------
T9600      CON   84

' -----[Mainprogram]------------------------------------------------------
PAUSE 1000

SEROUT TX,T9600,["AT",CR]
SERIN RX,T9600,[WAIT ("OK")]
DEBUG "Test communication ---OK", CR
PAUSE 1000

SEROUT TX,T9600,["AT+CMGF=1",CR]
SERIN RX,T9600,[WAIT ("OK")]
DEBUG "AT+CMGF=1 Set messagetype---OK", CR
PAUSE 1000

'SEROUT TX,T9600,[CR]
PAUSE 1000
SEROUT TX,T9600,["AT+CSCA=",34,43,"4670xxxxxxx",34,CR]
SERIN RX,T9600,[WAIT ("OK")]
DEBUG "AT+CSCA=","Set message central number: +4670xxxxxx ---OK", CR
PAUSE 1000

'SEROUT TX,T9600,["AT+CMGS=",34,"070xxxxxxx",34,CR]
SEROUT TX,T9600,["AT+CMGS=",34,"070xxxxxxx",34,CR]
DEBUG "AT+CMGS=","Telephone number: 070xxxxxxx ---OK", CR
PAUSE 1000

SEROUT TX,T9600,["This is a test message from a NOKIA N12i GSM-module" ,26]
DEBUG "Message Sent!!!", CR
PAUSE 5000

END