History of the Western Electric 1500/2500

Introduction

Although some various production changes and tweaks would occur over the years, the basic design remained almost totally unchanged from 1964 right up through the divestiture of AT&T in 1984.

The vast majority of telephones made by Western Electric were made for the Bell System, although they also made special models without Bell System markings for independents, which were sold through Graybar. Western Electric also made some special models of the 1500/2500 for military and government institutions. Those made for the AUTOVON system, for example, had 16 buttons, with the 12 buttons we are all familiar with, plus 4 additional ones for selecting the priority of the call.

Timeline

1964

• First year of production
• Initial 1500 models use a Type 25 touch tone dial, along with a model 425G network. The 425G is just like the 425E used in the model 500, except that it does not have the capacitor and resistor between the F and RR terminals that traditionally was used to suppress RF interference caused by the pulsing of the rotary switch contacts. NEED HELP CONFIRMING THAT THIS IS CORRECT.

• Turquoise is added to the color palette, for a total of eleven colors, including the ever-popular BLACK.
• ALL of the colors, including black, have hard plastic housings, plastic G3 handsets, and clear plungers???? I'M PRETTY SURE OF THIS, BUT I NEED CONFIRMATION.

1965

• Shifted from black paint to yellow cadmium plating on the bases.
• Shifted from triangular rubber feet to circular rubber feet
• Shifted to smaller handset cords???? NEED CONFIRMATION OF THIS.

1968

• Shifted from the 10-button Type 25 dial to the 12-button Type 35 dial. With this change, the model number also changed from 1500 to 2500.
• The bases and handsets on all models made for the Bell System are now stamped with the words, "Bell System Property, Not For Sale."
• Shifted from the 425G network to the 425K network. The 425K network is just like the 425G, only with the addition of two more dummy terminals, "S" and "T", which are not internally connected to anything. They are added specifically for the hookup of the TT pads, and eliminate the need for separate terminal strips under the TT pads, as had been employed with the 425G networks. NEED CONFIRMATION THAT THIS IS THE ONLY CHANGE MADE IN THESE NETWORKS.

1975

• Shifted from the 425K network to the 4228 network. The circuit in the 4228 network package is fundamentally just like the 425K network, but with these differences:
  • Unlike the 425 networks, the 4228 is not potted, although it is still hand assembled, in contrast to the printed circuit networks employed by other makers of the 1500/2500, like ITT, Stromberg-Carlson, and Northern Electric.
  • The induction coil specs are changed a bit.
  • The value of the resistor in the sidetone balancing circuit is increased a bit.
  (THIS IS NOW CONFIRMED. THE LATEST 425K NETWORK DATE I'VE SEEN SO FAR IS 1974, AND THE EARLIEST 4228 I'VE SEEN IS DATED 1975.)
• Shifted from hardwired to modular line/handset cords????
• Changed the style of date coding. Instead of "mm-yy," it is now "yyddd," where yy = year, and ddd = the day of the year. IS THIS THE YEAR THIS HAPPENED?

1983

• Shifted from Type 35 dial to Type 72 dial. The Type 72 dial uses 10-transistor IC chips in place of the old tuned inductor coils and capacitors, and uses single contact points for each button instead of the crossbar-like row/column contact mechanisms employed in previous dials. The Type 72 dial is generally not well regarded for its tactile feel or its reliability, compared to previous dials.
• Shifted from the 4228 network to the 4293 network. All I know is that the 4293 network is similar to the network found inside the Trimline phones. Compared to the 4228, it basically sacrifices some performance to gain lighter weight, smaller footprint, and lower cost.
• Introduced customer-owned models with "CS" prefix. They are pretty much identical to the traditional rented models, except that they lack the "Bell System Property, Not for Sale" markings. IS THIS THE YEAR THIS HAPPENED?

1984

• Production under the Western Electric name ceases, with the divestiture of AT&T. Production of customer-owned "CS" models continues a little bit longer under the "AT&T Technologies" brand.

Today

• Production continues under Lucent, and now under Avaya, albeit with the K-style handset instead of the venerable old G-style handset.

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