[Asterisk-Users] telco access ?s -- PRI, T1, POTS?

[john lawler]

Hi guys,

I'm new to the telco game and still pretty new to Asterisk, although 
I've been using it for a couple of months now and like most of what I 
see.  At my office, we've got a small two extension setup w/ two Digium 
cards for a single FXO line and three FXS extensions, but I'm also 
working on designing a larger installation for a customer which will 
involve ~16 analog handsets that I'll be running through a Rhino 
Equipment channel bank to a Digium T1.  My question is all about what 
type of phone service would be recommended for my local provider.

I purchased a CAC FXO channel bank to interface with a second Digium T1 
card that I've got, and ran some small scale tests on that which seemed 
to go fine, and I'm sure this solution would be *sufficient* for the 
customer, but I know he would like to be able to do DID, which, from 
conversations w/ SBC in my area, I've discovered requires something 
other than POTS.  We'll be looking to have roughly 10-12 phone lines for 
both inbound and outbound (as you'd have in the POTS world), or w/e the 
PRI, etc. equivalent would be.

So the real question is, from all of your experience, assuming my local 
telco can provide me w/ any possible solution, what would you all 
recommend I choose?  Some sort of fractional T1 line w/ DID trunks for 
incoming and POTS for outbound calls (pardon my description of these 
solutions if they are inaccurate--again, I'm new to the game) or what 
else? 

The other main point I should make is that both the customer and myself 
are interested in a solution where we could, in an emergency, or in the 
event my configuration of Asterisk is inadequate, switch back over to a 
situation where we could at least place and receive all calls using the 
analog handsets.  (E.g., from what I know about this stuff, I suppose I 
could plug the Rhino FXS channel bank into an incoming T1 line which 
would then split all the lines into analog which my phones could then 
plug right into--of course, if I went w/ a straight POTS solution, we 
could obviously just plug 10-12 of the analog handsets into the lines 
and at least answer the phones (albeit in a haphazard manner)).

I apologize for the length of this question, but I figured some of the 
knowledgeable people on this list would've had some experience in these 
areas.

Thanks,

jl