Nortel Norstar and BCM Lore


Northern Telecom was a manufacturer of telephone equipment, from circa 1900 to circa 2010. They were originally the Canadian arm of the Bell Telephone empire. Commonly shortened called "Nor Tel" or "NT", they formally changed their name to "Nortel Networks" in 1998. In the first decade of the 21st century, Nortel collapse financially. In 2009 the telephone equipment business was told to Avaya, and most of the products discontinued.

Before all that happened, though, I got to know their smaller telephone systems pretty well.

Nortel Product Lines

When it comes to telephone systems, Nortel basically has three product lines:

Norstar/BCM are usually called "key telephone system" products, but like many later key systems, they can be configured to operate more like a small, simple PBX than a traditional key system. See PBX vs Key for more on the distinction.



BCM = Business Communication Manager
MSC = Media Services Card
MB = Media Bay
MBM = Media Bay Module
BFT = Base Function Tray
AFT = Advanced Function Tray

The BCM used to be called "Enterprise Edge" way back when. Presumably Nortel originally saw it primarily as a way to connect field offices to a Succession (CS1000) at headquarters.


The MSC is basically a Norstar KSU on a PCI card. That's where most of the phone functions take place. That card also serves as the gateway to the telephony applications which run on the PC, which include all IP-based trunking and stations, voice mail, auto attendant, and so on.

Most of the BCM models look like a commodity IBM-PC computer at first glance. That's because they are basically built on a commodity IBM-PC chassis. Instead of 5.25-inch drive bays, we have MBs, but those are even about the same size.

The MBs connect to the MSC via dedicated internal wiring. Conceptually, it's similar to the DS16 channels from a Norstar, except they can carry up to 30 channels to a MBM.

The MSC also has onboard slots for daughter cards (they appear to be PCMCIA-type). The main (and possibly only) cards seen are for voice compression. I expect they're DSP co-processor cards to handle (de)compressing IP audio, to and from the MBs.

The host PC ran Windows NT in older releases, Linux in newer. It normally ran headless; even if you connect a monitor there's not much to see or do.

BCM models

BCM models (in order of release):
BCM 1000 = The original
BCM 400 = Basically a refined BCM 1000
BCM 200 = Basically half a BCM 400
BCM 50 = Small form factor, built-in ports, no built-in media bays
BCM 450 = Basically a BCM 400 on steroids

The bottom half of the BCM 400/450 chassis is basically the same as the entire BCM 200 chassis. You have the BFT, which holds the motherboard of the PC, along with the PCI slots on a riser card, plus two MBs on the right.

Where the BCM 200 has nothing, the BCM 400/450 have the chassis repeated again, giving you an additional two MBs. Where the BFT would go you have the AFT. The AFT is where the RAID controller and second hard disk go for the mirror disk configuration.

The BCM 50 was somewhat different. It was an embedded system, lacking obvious PC features. The main unit came with built-in station and trunk ports. An optional expansion unit allowed a single MBM to be connected.

The BCM 1000, 400, and 450 also support an optional BCM 1000e expansion chassis, giving you an additional six MBs. The BCM 50 and 200 do not support the 1000e.

Other notes

While the DS256 jack may look like an Ethernet port, it's not. In particular, you *must* use Nortel's cable to connect to an expansion chassis. Using some random UTP cable you have may work at first, but you'll get random MBM failures. It's apparently very sensitive to timing, so it has to be the precise length Nortel cuts it to.

Be warned that you need more than physical space to plug in MBMs. You also need resources on the MSC. You generally won't be able to fully populate all ten possible MBs, except *maybe* with a BCM 450.

The BCM has some built-in CDR capability. That's Call Detail Recording, i.e., logging of each telephone call placed using the system. I have a write-up on how to get the BCM CDR logs in an automated fashion.