[lug] Connecting Mobile to Linux

I want to connect a mobile phone to Linux Machine what do I need
to know to be able to do so what should be studied any one here who
has done any such sort of things I would like to programm a chat
software to be able to do so I mean like in yahoo messenger we have an
option to send a SMS online I want a PC in Linux to be able to do so by
connecting a mobile phone to a PC with Linux and should be able to talk
using that If any such sort of thing has already been done then tell
me a link where I can study that