IC that can detect on-hook, off-hook, ringback, busy signals

Hello, can anyone suggest an IC that can be used to detect on-hook, off-hook, ringback, and busy signals?

it is easy to make a circuit wich tells you if the phone in on/off hook, and maybe when it is ringing, but i dont know about the busy tone......
you can do the first three with some transistors base on the voltage that you have on the line...
highter dc for on hook , smaller dc for off hook, high ac for ring....