asterisk users - Jan 2005 - asking for readers input into the following config...

The company I work for has gotten the go ahead to start dipping its foot
into the shallow end of the asterisk pool. The client we will be setting
up for currently has an NEC PBX of some sort with 8 analogue lines in.
They use lines 1-4 as indial on a rotary group, lines 5-6 as indial for
two 1800- numbers (1800 is Australian prefix for freecall), and lines
7-8 as outgoing. There are approx 15 extensions using some sort of
non-standard handset.

During the quiet period for this client (the rest of January) we will be
configuring asterisk on a new E1 service with a few analogue and a few
VoIP extensions. The current analogue lines to the NEC exchange will be
fed from a FXS card from asterisk, meaning that all outgoing calls will
be via Asterisk.

Here's a really bad ascii diagram

1 2 3 4 5 6 <- Analogue lines from exchange
| | | | | |
Existing NEC PBX
| |
7 8
| |
Asterisk
| | |
| | C <- E1 (10, 20, or 30 lines)
| |
A B <- Analogue lines that used to connect to 7 & 8 on the NEC PBX

This will also allow a limited amount of call transfers between the two
systems.

The client is well aware that this is a trial of Asterisk, and the
beauty of all of this is that should they be unhappy with it, they can
re-connect the two analogue lines back into the old PBX and pick up
where they left off.

They will be getting a new PBX anyway, be it Asterisk based or not, so
the purchase of the E1 line won't be wasted either. The hardware
purchased will just be retained by my employer if the client doesn't end
up using it, and we'll learn from our mistakes and try again some day so
it will be used eventually.

Any comments?

Also, what do people do when it comes time to do an update, be it for
security or bugfix reasons? Are there any tricks to doing a rollback
should the new version prove more buggy than the previous?

Thanks

James