[Asterisk-Users] Advice on BT ISDN Services (UK)

[Nick Barnes]

Benjamin asked:
> I don't have a problem setting this up under Asterisk (that's 
> the fun part) but what I need is advice on what to ask for 
> from BT so I don't get the wrong lines / services and so that 
> it all works smoothly! 

OK. You need one of the following:

Home Highway
Business Highway
ISDN2e

I can confirm that * works happily with all three - my office lines are (for
various reasons, none of which apply any more!) on Business Highway.

If you want to use a Fritz! card, then you MUST have the line set up in PTMP
(point to multi-point) mode. Home/Business Highway only work this way, so
that's not a problem, but ISDN2e can be either PTP (point to point) or PTMP.

BT PTMP only supports MSNs (which you can have a maximum of 8). PTP only
supports DDIs (which you can have as many as you can afford). Essentially,
if you order ISDN2e with MSNs you'll get PTMP and PTP if you order it with
DDIs. I gather (although I have no experience) that if you order it without
MSNs or DDIs, you'll get it in PTP mode, so make sure you specify that
that's not what you want.

If you want sequential numbers, then you'll have to argue like mad to get
them as MSNs (I managed to get a block of 5 sequential MSNs, but it was hard
work!). DDIs are issued in blocks of 10 and are usually sequential.

My first * box was built with a Fritz! card from eBay and configured with
chan_capi, but I have now moved over to the HFC cards and use zaphfc which
works like a charm. HFC cards are available from Komplett
(http://www.komplett.co.uk/k/ki.asp?sku=119006&cks=SER) for £13. The HFC
cards support both PTP and PTMP modes.

The other thing to watch out for when you order the lines is which rental
option you take out. BT offer three different options ('start up', 'call
plan' and 'low start') each with different installation costs, rental
charges and call allowances - if you don't specify which one you want,
they'll pick one for you (and probably at random).

Have fun, and if you want to talk off-list, please feel free.

Cheers,

Nick Barnes
Senior IT Consultant.