[Tutor] Telephone app

[David Hutto]

> Can you step back a bit and explain what it is you are trying to
> accomplish? "flow through" and "functional flow through" are meaningless
> terms in telecomms - at least so far as I am aware (after my 35 years in
> telecomms engineering...)


It's two fold. First is the obvious of conducting a call/receiving the
caller id info. The second is to send directly to the phone, and
transmit the caller id data.

By flow through, I mean that the phone has one of 2 states(on the
hook, off the hook), and three sub states(on the hook/off the hook in
use/off the hook not in use).

On the actual phone we pick up the receiver, or press the button on
the cordless to receive, but the line is always connected, meaning it
stops at the phone(terminal). I pick up the receiver, and transmit a
series of specific tones which indicate the area code, trunk number
and extension(if I remember this correctly, it's been a while since I
studied the phone itself).

So I have to receive the signal that the phone is ringing(then I'm
assuming it sends the caller id info in between rings in some form)/or
transmit a series of tones to them to connect.

So I think my main question is what modules might be relevant to doing
this? And should I be thinking of it any differently than a USB port
which has 4 pins two data(+-), and two dc current(+-)?