check this
http://www.sonsivri.com/forum/index.php?topic=13194.0but there is an easier way, find an old gsm phone enable the "quick dial" example if you press No2 for more than 2 sec it dials a specific number etc. open the cover and connect in each button you want 2 cables connect the to a solid state relay or to a simple relay and trigger the relay from your microcontroller. i have made this project and works fine for over 5 years and costs almost nothing if you want i can send you the scheatic.