hook off,hook on,...phone circuit HELP

hi,
my project is home automation
can any one give me circuits to control the hook off and hook on and ring detector and busy tone detector


THANKS FOR ALL

when all phones are one the hook the voltage on your phone line is 48 volts when someone picks up it goes down to 12 volts. It should be quite simple to make something with this. If you can't work anything out email me at dcat127@yahoo.com