[Asterisk-Users] DID/T1

[George Pajari]

> So DIDs are sharing available channels.

Not necessarily -- you are confusing two separate concepts:

1: DIDs are a mechanism for having more than one phone number that can be
routed to one or more voice channels and for identifying which number was
dialled when a call is presented by the CO. Depending on the part of the
world you are in and the technology used, this mechanism may be referred to
as DDI or MDN (Multiple Directory Numbers).

Sharing available channels is the ability to have incoming calls (to the
same number or different numbers) routed by the CO to more than one channels
depending on channel availability and the rotation algorithm used by the CO.
This is usually referred to as "rotary", "overlines", or "call forward
busy".

> In particular for ISDNs are DIDs sharing available channels?

Let's deconstruct this question into its component parts.

(a) Can ISDN support DID numbers?

Technically yes. Whether or not your telco will provide this functionality
is a question only your telco can answer. We have seen telcos that would not
provide DIDs (or MDNs as they are usually called with respect to BRI
circuits) on ISDN BRI circuits but would on PRIs.

(b) Can ISDN support "overlines".

Technically yes. Your telco may, as above, be less cooperative. Again, our
experience is that the possibilities with PRIs are greater than BRIs.

In short -- you will have to talk to your service provider (or change
service providers) to get what you want. Hope this helps.

George Pajari
www.netVOICE.ca
www.ip-centrex.ca