I’ll be honest, my IT background and bread’n’butter for 15 years was primarily Exchange. OCS/Lync presented an interesting opportunity to expand my Exchange horizons with the integration of UM and ultimately into Unified Communications. I do not have a background with telco’s, though I have set up a couple of RightFax servers (just dated myself there, no idea who owns them now, still Captaris?!?) with Brooktrout boards using PRI lines. Needless to say, I’m not an expert when it comes to ISDN. The first company I worked for was a law firm running ISDN 128k data line for internet and one of the first things I discovered for the firm was LAN connection to the internet, 10 Mb, it was lightning. 18 years later and ISDN is still around though mostly for voice I would. (I bet you just figured out why it’s UCC Ramblings didn’t you)
Anywho, a recent telco experience let me to do a bunch of research as to why we were having so many problems with our PRI line connection with an AudioCodes gateway. When requesting of the telco what protocol type, clock master, line code… they insisted it was NI1. Things did basically work (smarter people than me will probably have picked up on what I said there) but there were warnings/errors in the sip traces. You could make and receive calls the usual, BUT something was missing, the Display name, blank, always blank.
After performing a PSTN trace for the AudioCodes engineer to analyse, there was lots of data missing, and things really didn’t look right. The request came back, try DMS100 or NI2. But telco says it’s NI1 times 5, very insistent. What the heck, I set up amazing routing in S4b to have outbound calls go out 2 different gateways, no worries. Low and behold changing from NI1 protocol to DMS100 was the silver bullet. Errors gone, warnings gone, Display name appears, woo hoo. New PSTN trace showed the Display property being used, and not a Facilities method like in NI2. Very definitely a T1 DMS100 ISDN line.
Now I’m perplexed, I’m GenX, i need to know the why. Few days of reading later, I know more about ISDN then I ever care to, I much prefer SIP trunking, but if you don’t know where you came from, how will you know where you’re going…
ISDN has been around since the ’70s, DMS100 was developed in 1979. Resiliant little protocol built in a time of efficiency where every bit mattered. blah blah blah – here’s a link: ISDN NI1 was developed to standardise BRI lines (Basic Rate Interface), hmmm, basic, I think I mentioned that word before. NI2 was developed for PRI lines (Primary Rate Interface).
I don’t know the history, or the reasoning to why a certain telco insists on selling their PRI lines as either NI1 or NI2. I’ve only seen NI2 out west to be honest, and the first “NI1” trunk that I’ve see happens to be out east. I’ll blame the sales guy who first started creating the database and ordering system. Or maybe they’ve forgotten too, I’ll have to post the monkeys-in-the-cage analogy sometime.
Summary: In Canada anyway, if a telco says to use NI1, there is a very high probability that it’s actually DMS100. Or if you just can’t get an answer, try DMS100 and if its not working out, then go NI2. If you’re still out of luck, the NFAS is possibly in play and you definitely need to talk to the translations engineer to find out more.