Historical Notes on the Carrier Switches on Avaya Red PBX systems

Originally part of the Tribute to System 75, relocated to a blog post, with an update since it’s original post in 2015.

The System 75 was a fully new system that could handle infinite technologies such as ISDN, PRI, T-1, and later IP and packet switching. At the same time, AT&T also marketed the not so bleeding edge PBX called the System 85, which was a Band-Aid version of the Dimension. But this version would use shared hardware compatibilities with the System 75. In fact the System 85 had some interesting features such as AUDIX “Unified Messaging”, ports could max out to over 30,000 extensions and support up to 40 attendant consoles. Well, not the 302 console I posted earlier, but a boxy one that was used for the Dimension, so boxy it earned the top 6 position as the Ugliest Operator Consoles in 2016 from this site.

Another system called the System 25 was based almost entirely on the Merlin system with the code, and features. The System 25 is much comparable to a Merlin Magix or Legend system of today, which eventually replaced this odd setup.

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New Virtual Exhibit – A System 75 PBX Article

I’ve been lucky to obtain access and finally got to the Holy Grail of modern office telephony – that Avaya’s marketing department would never want you to know! We like to focus on other systems, and platforms like the ESS for an example, but what me interested in phone systems in general was the AT&T era of the 1980s.

Thanks to the N.H. State Library, and Rebecca, one of the reference librarians, I got access to the book taking a recent trip to Concord and got nearly 100 pages worth! AT&T at the time which sold the System 75 (later named the Definity ECS, MultiVantage, Communication Manager to Aura, marketed by Lucent and Avaya over the years) did an entire tell-all of how they developed the system, how they developed it, the hardware background, the software background and how they ate their own dog food, as some AT&T sites were the first test groups. Developing the System 75 from concept to market took about 3 years and was on the market by the time of the publication in January 1985.

Despite the 30 year old publication, the kernel and hardware architecture basically remained the same and such architecture helped its way through newer technologies such as ISDN, packet and IP switching and later Voice over IP. It was this concept and system that would have descending companies tout 90% of the Fortune 500 wither company wide or a few locations using this type of communications using the System 75/Definity/CM/Aura platform. It wasn’t really until the last decade did such entity (Avaya) tout such customer base, which probably has eroded significantly under companies like Microsoft and Cisco with their “unified communications offerings”

I’ll be posting this little by little over the course of the next couple of months, with my own take. It’s surprising it wasn’t a form of a white paper or publicized elsewhere, it’s a great read and it’s a rare find, my job is to make it easy for the people who would be so interested in reading this.

Stay Tuned!