Analog phone to GM862

Hi, I was wondering if there is a project out there which allows to hook up an analog phone (FXS) to the GM862 to make data/voice calls. I saw the rotary phone project but, I was looking more for something like a general solution emulating dailtone/busy signal etc. There are some devices like http://www.ericssong32.com/ out there - this is what I mean.

Thanks for any hints.