On Thu, Mar 09, 2000 at 02:06:49PM -0500, Ken Hornstein wrote:
> >I also need a copy of the NI-1 specs; pointers to that would be helpful
> >too. I don't even know which document I need... is it TR-NWT-000776 from
> >Telcordia?
> 
> I was told (when I inquired about this a couple of years ago, in a
> different context) that having the NI-1 spec isn't quite enough.  What
> you really need is access to the source code that runs on the switch so
> you can figure out what all the undocumented extensions are :-(  I
> gather this is especially true for things like the so-called 5ESS
> protocols.  From what I understand, there are only a few people who
> write US-compatible ISDN stacks and most companies buy one of these
> stacks.
>
> This was told to me by someone who had helped author ISDN specifications,
> so I treated it as reliable.  However, don't let that stop you :-)

I've written low-level ISDN software and I *certainly* don't consider
that to be reliable advice.  A copy of the Telcordia specs and, at most,
a few days with an ISDN protocol analyzer (I have access to a very good
one, if you're in dire need send me email) should do the trick.

Before NI-1, you would have needed access to the documentation (you *never*
would have gotten your hands on the source code) for the switch you were
talking to.  This wasn't _too_ hard to get one's hands on, though expensive
and occasionally somewhat incomplete.  Also, some switch vendors 
(particularly Nortel) implemented call control so minimal it was almost not
ISDN.  NI-1 forced them to get it (more or less) right by mandating most of
what the 5ESS had always been able to do.

But pretty much everything does NI-1 now, and NI-1 isn't too bad.  If you're
doing Primary Rate, there are still a number of things kicking around out
there in the network that don't do NI-2 PRI (PRI was not in the NI-1 spec)
but the most common is the 4ESS, and if you're an AT&T customer with a PRI
from a 4ESS you can get all the documentation you'll ever need directly
from AT&T.

-- 
Thor Lancelot Simon	                                      tls@rek.tjls.com
	"And where do all these highways go, now that we are free?"