[Asterisk-Users] yet another question on DID trunks

[john lawler]

Hey Steven,

Sorry to bother you yet again w/ a question on my seemingly endless 
quest to get DID trunks setup for a customer.

If you don't know anything about this issue or would rather I looked 
elsewhere (including the Asterisk list, I suppose), please just let me 
know right off the bat.  I'm having great difficulty finding good 
resources on the web that explain this technology.

I'm still trying to examine a DID solution for this customer but don't 
understand how a single trunk (whatever that is--I assumed just a single 
pair of wires like a POTS line, but I'm thinking now it must not be) can 
support multiple (incoming) phones calls.  I've also been told how many 
phone calls per trunk depends on your equipment.  Do you know anything 
about equipment that interfaces with DID trunks?  Are there special 
devices that do this?  I think I've heard about FXS port devices 
supporting DID.  But how could a single FXS port (say on a channel bank, 
or even one of the Digium PCI FXS cards) support multiple 
conversations?  Asterisk would certainly just see it as a single channel.

Anyway, those are the questions I've got at the moment based on my 
(lacking) understanding of how DID (and other) trunks operate.  I've got 
two Digium T1 cards, a Rhino Equipment FXS channel bank and a Carrier 
Access channel bank w/ 2 - 12 port FXO cards in it.  And I'm just about 
ready to start testing that system, but I want to determine the 
additional difficulty + cost of using DID trunks for inbound calls 
instead of POTS lines.  Oh, and the other disclaimer is, fractional T1 
is not an option for me, so these'd have to be "analog" DID trunks, or 
whatever the default way of receiving them is.

Thanks a bunch for your help, and please refer me elsewhere if you don't 
have the time for this query.

jl