closed its USA consumer telephone manufacturing plants in 1986 and moved production offshore to Singapore, China, and Thailand, and in the 1990s to Mexico; this let them produce telephones at a lower cost. Design features The Western Electric model 500 improved upon several design features over the earlier telephones. While the 302 had the dial and hook switch mounted directly on the metal or plastic housing, all operational parts of the 500 telephone were mounted on the base plate, and the housing only contained two plungers to activate the hook switch when the handset was lifted from the cradle. Thus, the phone could be tested and serviced easily without the housing. This design improved manufacturing and servicing efficiency. The earlier 302 had been equipped with an enamel-coated dial plate that displayed the numerals and letters through the holes of the rotary finger-wheel. Years of use caused the lettering and numbering, and even the porcelain coating, to wear off. The design of the 500 improved this by molding the characters into the plastic through a double-injection molding process. This design was carried over to the 1500 and 2500-series telephones and was used in the touch-tone keys to eliminate wear. The numbers and letters on the 500 were moved to the circumference of the dial plate to make them visible from a wide range of viewing angles even while the dial was spinning back to its resting position. Dots were placed in the center of the finger holes as targets to help position the finger quicker for dialing of the next digit while the wheel was still spinning back. After extensive testing, this arrangement had the benefit of reducing dialing errors and increasing the speed of dialing each digit by fractions of a second. The 500 series replaced many metal parts, especially in the dial, with much more durable Nylon components. The Dreyfuss design later adapted itself well to touch-tone service, first announced in 1963. The earliest experimental touch-tone phones used the original Dreyfuss design almost unchanged; the keypad, in varying layouts, was placed in a roundel in the dial opening, with the subscriber number label in a small window below. The 1500 and 2500 models adopted a more angular design style; the curves of the original design gave way to raised borders forming a lip around the finely-ribbed faceplate, in the middle of which the keypad and number window was centered.