Re: [Hampshire] Primary Rate ISDN (plus a bit of Asterisk)

On 15/03/07, Nick Chalk <nick@???> wrote:
> My other post describes our working Asterisk
> system. However, this being The Society of St.
> James, we're now going to change things.
>
> The project I wrote about in the other post is
> only in temporary accomodation. Within a couple of
> months, it is to move to a new, larger building
> which it will share with a second project, and it
> will merge with a third project.
>
> The resulting behemoth will require extensive
> phone services - they're all heavy phone users.
> So, a few analogue lines just won't be enough, and
> I'm looking at PRI, or ISDN 30 as BT calls it.
>
> I wondered if anyone here had experience with
> installing PRI, PRI interface cards, or even
> running Asterisk on ISDN?
>
> We're looking at eight lines initially, with two
> public numbers. DDI isn't essential, so if we can
> get away without paying for it, so much the
> better.
>
> With excellent timing, voip-info.org has gone
> down. BT's site is up, but - as usual -
> contradictory and confusing; I'll be on the phone
> to them again tomorrow.
>
> I'd be grateful for any advice or war stories.
>
> Thanks!
>
> Nick.
>

ISDN PRI can be very difficult to set up.
This is mainly due to * being all set up for the US ISDN, and not well
tested with the UK ISDN. I would therefore recommend only using the
ISDN PRI cards that * recommends. But, if you get the line up, without
any alarms (I.e. Layer 2, line not syncing up or not keeping sync)
then the Layer 3 (The actually ISDN calls) is easy.
You will not get any of the problems with lack of answer detect etc.
as ISDN gives explicit out of band signaling for that.
You will want a number of different numbers assigned to the ISDN30
line. These numbers can then be used for DDI. Any of the 30 ISDN
channels can be used to receive or send on any of the numbers.

I used to work for a telco equipment supplier, so I do have extensive
knowledge of ISDN if you have any further, or more detailed questions.

James