> One of the many areas that I am unclear on is if we can use
> the existing phones from the old PBX system? Some are Meridian
> M7310 and some are Norstar M7208 models.
Nope. Those are proprietary digital keysets and will only work with
Meridian/Norstar control units.
> They each support multiple lines with a multi-line display, but
> I haven't seen anything on this list about sporting multiple
> lines on a single phone...
There are phones out there that have more than one line appearance, like the
Cisco 7940 or 7960 (with 2 and 6 lines respectively). One thing I'm
personally not clear on is having what's commonly known as "multi line
appearance", where phone A is extension 201, phone B is extension 202, and
they both have an appearance of 222 which would appear/ring on both phones.
The other type of multi line appearance is where 201 and 202 have
appearances of each other. A call to 201 would only ring phone A, but phone
B would have a light lit up to show that phone A is in use. This isn't an
Asterisk specific thing, it goes back to the SIP standard/specification. It
might be easier with MGCP, I'm not sure - I remember reading something about
it but it was a while ago.
Hope that helps.
Paul