Introduced in 1950, the Western Electric 740E Dial Private Branch eXchange was a step-by-step dial PBX for small to medium sized organizations typically requiring fewer then 100 extensions. A manual switchboard, power and other miscellaneous equipment were part of the complete system. Our 740 saw service at the Kennebec Pulp and Paper Company in Madison, Maine and is a two-digit dialing switch. After being removed in the mid-1970's it saw service in the private residence of Dave Thompson for next 15 years (they just don't make things like they used to!).

A friend of Jeff Webber's, then of Island Telephone Co. (Frenchboro), was a CO man for New England Tel. & Tel. Co. and was helpful in giving Jeff bits and pieces that Bell was "junking out". He informed Jeff that the paper mill had a new crossbar PBX and the old 740 was sitting up there on the third floor of the office building. The two men talked about using it for a central office. In those days there was no direct distance dialing (DDD) in Hancock and Washington Counties and the initial proposal for Frenchboro was simply to have two ZTSTW trunks for connection to the toll network. Maybe this would work. Jeff discussed this with Dave Thompson, a fellow independent telephone man. Back then, the general attitude in the Bell System was they'd rather junk equipment than let an independent get hold of it. But something like this could be done quietly on a personal basis. After all, they knew that the old switch would ultimately be junked out. Why not let some poor struggling independent get some use out of it? Lawrence M. Noddin worked for New England Tel. & Tel. as the Bell-Independent Relations Supervisor for Maine. Jeff was shocked to get a call from him saying he heard that Jeff was trying to get the 740 and that RULES WOULD BE BROKEN if he did so! Jeff and Dave concluded that with DDD on the horizon, as well as other factors, it would be really difficult to make the 740 function as a full-fledged central office.

Meanwhile Dave was looking forward to starting his own telephone museum and the 740 would be nice to have. One Saturday, Jeff, Dave and a third man, drove to Madison with a utility trailer in tow. They had to get the switch off the third floor and down stairs turning at right angles as they went. Fortunately they were able to unjack the switches and a few other components to lighten the frame and carry those things down separately. It was a struggle but the three got it down, and into the trailer and headed back to Dave's place in Morrill. They ultimately got it into his cellar, no easy task in itself.

After being idle since 1989, the 740 was donated to the New England Museum of Telephony around 1995. Dave and his wife Barbara were by then museum "subscriber" 11 (Jeff Webber is subscriber 12). It would remain in storage for another five years. In the fall of 2001 the 740 was brought out to the Step-by-Step demonstration area of the main building. Charlie Dunne resurrected the machine by bringing power from the No. 3 Crossbar office power plant, and tying it to the 701 ringing plant. Two extensions were attached to demonstrate and exercise it. In the spring of 2002 the 740 would see the return of Dave Thompson for cleaning and maintenance. A third extension was added that summer for the 6th annual Telephone Fair.

In preparation for the 7th annual Telephone Fair in 2003, Stan St.Onge and Chad Perkins cleared the switch of old cross wire and installed a new 25 pair cable to the terminal in the step-by-step area. This opened up the entire museum cabling plant to the 740 and three more "extensions" were added. Extension 55 was run to a trunk position on the Kennebunkport 555 switchboard. However awkward, this allows us for the first time to be able to place calls through the toll operator at Kennebunkport to anywhere and vice versa (the real attendant trunks still await restoration). Extension 47 was run to the outdoor displays to facilitate traffic to the other extension installed for fair last year (48). Because this switch is being demonstrated as the PBX that it is, extensions are not in the telephone directory for the museum. To compensate for this a third extension, extension 22, was run "backstage" to an automatic answering machine with a modern-day-sounding dial-this-for-that company directory. Tonya Perkins made up "cards" for placement by the appropriate telephone sets alerting visitors (and staff) of the company directory and the number to dial.

In the 740E step-by-step dial PBX, the line relays, line finders and selector-connectors together with miscellaneous trunk units are placed on one frame called a line frame. The line finders have banks with a capacity of 100 lines as contrasted with those used in the 701A dial PBX which are used with groups of 200 lines. One line frame has a capacity of 78 lines when two levels are used for trunks as is the usual case.

The selectors, when required, are arranged on a separate frame. When more than 78 lines are required, a selector frame is added and the original line frame is built up to a capacity of 98 lines. This is accomplished by disconnecting the wiring between the line finders and the selector-connectors and running cabling from the line finders to the selector frame and from the banks of the selectors back to the selector-connectors on the line frame. The selector-connectors thus become connectors for the lines on that frame. Additional line frames are similarly treated up to a normal capacity of 300 lines.

The switchboards, jacks and trunk units used with 740E dial PBX are the same as those used with the 701A dial PBX. However, there is a small capacity desk type switchboard that may be used where only one position is required and less than 100 lines are contemplated.

From Survey of Telephone Switching - Chapter 13.
For the full text go to http://www.telephonetribute.com/switches_survey_chapter_13.html