Blog for Telephone Projects


September 16, 2019

I’ve been collecting telephones and telephone switching equipment for a bit over 10 years. Recently I acquired my first substantial example of an early 20th century private automatic exchange or P-A-X. I thought that this would be a good opportunity to document my hobby and the things that I’ve learned along the way.

In a way, this really started much more than 10 years ago, when I was just five or six. My grandparents both worked for the telephone company, my grandfather was an installer for Western Electric and my grandmother was a switchboard operator in Baltimore before they went automatic. To keep me occupied one day, my grandfather hooked up two old switchboard headsets, a six volt battery and a bunch of wire and we each took a headset to opposite corners of the back yard. Some time later I got two army field telephones from a flea market and we repeated the experiment.

However, it wasn’t until I was much older that I became interested in other telephone equipment. In 2007 I was working as a network administrator for a small manufacturing company and we were in the process of upgrading the telephone and network cabling in preparation for a new VoIP telephone system. As part of this project, I removed several thousand feet of 25- 50- and 100-pair cable that had been left behind from the 1A2 key system that was installed when the building was built in 1981. At the time all I knew was that this was for those phones with the six square buttons along the bottom, but I didn’t know what they were called or how they worked.

Tucked away in the sprinkler valve room behind the mail slots was a small wall mounted rack with a power supply and a nearly fully populated 584C panel. It was plugged in and connected to several outside lines. There were no stations connected to it, nor had there been since at least 1995. I took it home. I didn’t really understand what it was or what to do with it, but I found a manual for the panel online (I think I paid $19 for it) and found someone selling 6-button phones.

When I hooked everything up, I was disappointed that it didn’t provide dial tone. And so I learned a bit more about 1A2. Enter Asterisk. This proved to be an interesting diversion, but finally I had dial tone. So I installed these phones and this key system in the house I was living in (and sharing with three other people).

But this got me interested in more complex systems. I wanted a mechanical telephone switch like the ones that I knew my grandfather had installed. Eventually some Automatic Electric step by step equipment turned up on eBay and I bought it. Again, I had little idea what I was looking at and less how to make it work. Nonetheless, it fit on the wall and was an interesting conversation piece.

About a year later, I moved and packed all this up and for about 10 years it stayed packed away in boxes under my basement stairs. From time to time I still bought interesting phones that I came across, especially 400-series key sets. Recently the opportunity to buy a 1930s era Automatic Electric Type 5 P-A-X presented itself and so here we are.

This Friday, September 20th, I’m heading to Cincinnati to disassemble, catalog and crate this P-A-X in order to bring it home to Baltimore. I will be documenting the process here with photos and video.

What little I know so far, I’ve received from the owner of the building. It was a factory built in 1935 for the Worthington Steam Pump Company for the manufacture – presumably – of steam pumps. The phone system was installed then. These AE P-A-X systems were standalone, strictly internal, telephone systems. They did not connect to the public telephone system, and this was marketed as a feature. It meant that the lines would not be congested with outside calls and also that it was completely private and secure since no one could be listening in. Or at least that’s how they sold it. I’m not convinced, but I didn’t own a business in 1935, so maybe these seemed like obvious benefits then. Automatic Electric did also sell P-A-B-X (Private Automatic Branch eXchange) systems which did connect to the outside world and also sold parts to convert P-A-X systems to support central office lines, so perhaps others were sceptical as well.

Some time later, Worthington moved out and the Cincinnati Butcher’s Supply company moved in and began manufacturing their BOSS line of industrial butchering equipment. They kept the P-A-X in place and continued to use it and have it serviced well into the 1970s. When the current owners bought the building the switch was no longer in use, having been replaced by crossbar PBX. They retired the crossbar system in favor of a modern digital telephone system, but being historically minded and not in need of the floor space, elected to keep both systems decommissioned in place.