If you are talking to one of those self-contained, postage stamp-sized GSM modules using a microcontroller, chances are there'll be a serial link to it, and it's listening to Hayes commands.
It's still there.
/me looks at this content-free page and then reads your comment
+++ATH0
ATDT
ATZ0E0M0L0&A0&D0&G0&K0&N1&U1
ATDT@;684-767-2676 (or any 767-XXXX, 555-XXXX is also fun)