How to send an SMS message from a PC with nothing more than a TCP/IP connection via ethernet?
I tend to use the following commands - look them up in the AT Commands manual:
AT+CMGF=1
AT+CSMS=0
AT+CNMI=2,1,3,1,1
AT+CSMP=49,169,0,0
You will also need to know your network’s SMS Service Centre (“Message Centre”) number, and set it using AT+CSCA
You can save these settings with AT+CSAS
You may also want to set AT+CMEE=1
Do any of the links at the end of this thread help you:
wavecom.com/modules/movie/sc … php?t=1142
awneil, thanks.
do you have any thoughts about questions 2 and 3?
Doesn’t developershome.com/sms/ cover that?
In particular, developershome.com/sms/howTo … romPC2.asp
Here’s a couple more gateway providers for you:
tiltd.com/html/txtranet.html - you can get a FREE account with 10 credits on it to test! 
and did you read about Kannel, mentioned here:
You can try this free sms software, that does a HTTP to SMS. You need to get a Wavecom modem to use it. 
You can also use Skype - see: viewtopic.php?f=21&t=1142&p=8445&hilit=skype#p8445
It may or may not work out cheaper than using a GSM mobile or module…
Note that it may not be necessary to set this explicitly - see: SCA for reply to received SMS? - #3 by awneil
at least i never needed to set this.