DTMF - MC145436 and answering machines

[Elven Commander]

Hi, I am making a project dealing with DTMF and taking a number that was inputed and using that number to do something. I am pretty new to this and have been doing an immense amount of research and came across a few questions.

1. I need to connect to the phone somehow to pick it up when I call in, and then to get the inputed numbers to my DTMF chip. So I was thinking hey, that is what answering machines do, I could probably just hook into one of those, where I can set the amount of rings it can do etc. etc. Does anyone see a problem with this? My major question was if anyone knew generally where to attach my addition into to get the input signal, web, expereince or whatnot, I was researching today, and was comming up empty handed.

2. I am using the MC145436 chip for DTMF, I have never created anything from scratch, and this is my first attempt. I was reading the data sheet, and understand most of it. I am unsure of the DV pin, and then the GT and Xen pins which appeared to me to be directly related. The GT is for Guard Time, Xen for an extermal oscillator I do believe (not in front of me at the moment) My other question with this is this: Some pins require a logic 1 (in my case the ENB) that means I just need to send my +5V from VDD into ENB aswell right?? or am i very far off track?

Thank you very much for your time

Jason