I required an SMS gateway to send 1-15 non critical SMS messages a day and produced this hack API to the Vodafone Web2TXT system. (You need a Vodafone.net.nz login to be able to use this.) Messages from this will be from your cellphone number so it makes it handy if you need to reply.
Perl, using LWP/SSL and a few tricks, performs the appropriate POST requests to use the Web2TXT system to send the recipient's cellphone an SMS.
Module Dependancies:
3 pages link to CommandLineSMS:
libwww-perl