Chronological Summary and Highlights, presented by model produced.
Click photos for additional details, if available.

This is a work in progress.  Please send additions and corrections. I'm sure there are many "missing links" to be discovered. For background, read the DEVELOPMENT OVERVIEW.
WE 1500 development timeline -- announced in 1964
	1948 Built in a 302-style case with F1 handset.  Two rows of 5 keys on the front plucked reeds to produce two tones for each digit.  2 out of 6 frequencies. Tested on the first No. 5 crossbar switch in Media, PA with families of 35 Pennsylvania Bell employees. Based on a design tested at Bell Labs in 1941 and put on the shelf during World War II. See also: A History of Engineering and Science in the Bell System, Switching Technology (1925-1975), page 166. After the transistor was developed, research turned to electronic oscillator designs. (Courtesy of Lucent.)
See "Tone Ringing and Pushbutton Calling," Bell System Technical Journal, March 1958, page 340.	? (pre-1958) Modified 500 set with a 10-digit crosspoint switch. 1 of 10 frequencies. Experimental tone ringer. In-house laboratory tests.  Limited field trials in Americus, GA and Crystal Lake, IL.
	1958 F-53176  11/58 Early prototype uses standard 500 components with a new dial pad. 2 out of 8 frequencies. (Image courtesy of AT&T Archives and History Center, San Antonio.) The DIST key signalled that the user was about to dial a 10-digit long distance number.  It was proposed to be included on ALL production tone sets.  If adopted, it would have required that all rotary sets be replaced!  (Sounds like eliminating analog cell phones and analog TVs today.)  Fortunately, they realized that if the user simply dialed "1" first, rotary phones could still be used.
	1959 F-53139  11/58 As above without "DIST" button. Note holes for clear number card holder. Technical trials in Hamden, CT (step-by-step) and Elgin, IL (common control) -- about 200 in each city. F-53140 "Display sample"  Dial mounted in a keyset. (Bottom image courtesy of AT&T Archives and History Center, San Antonio.)
	ca. 1959 Alternate button layouts From Bell System Publications
	1960 F-53700  4/60 Square buttons.  Revised pad. Technical Trials in Cave Spring, VA ((step-by-step) and Hagerstown, MD (common control) -- about 100 in each city.  Each line supported both Touch Tone and pulse dialing. Field Trials (marketing trials) in Findlay, OH (11/60) and Greensburg, PA (2/61).  Included desk, wall, Princess, keyset, Call Director and coin station sets with the same keypad.
	1962 Wall set prototype using a later pushbutton configuration. Installed in a standard 554 set, as in the Field Trials, above. From a Bell System ca. 1962 brochure.
	One of many wood models made to test various contours for the base shell of the 1500 desk set. (Courtesy of Lucent.)
	WE 1500D -- as announced in November, 1963 It got its own case with a "modern" facelift. The faceplate is seperate from the Touch Tone pad, so is easy to change if damaged, or to quickly change the set's color. Earliest sets had charcoal gray faceplates. Was previewed in 1962 at the Seattle World's Fair.  Debut at the New York World's Fair in 1964, with over 3500 phones and an exchange in operation.  Included 1400 phone booths with paystations and 10 "family booths" with speakerphones. Production started in 1963. For models produced, go here: WE 1500-SERIES
Princess (1702) development timeline -- announced in 1964
Back to Rotary Princess Development Timeline
	1960 F-53741 TouchTone Princess Set Photo found in a 1962 Bell System ad, "No end to Telephone Progress" Model number found on Trial Instruction No. 147, Issue 1, October 1960. Field trials in 1960 in Findlay, OH, 1961 in Greensburg, PA and 1965 in Suburban Chicago.
	WE 1702B -- as announced in 1964 The gray set is the Western Electric.  The bezel around the Touch Tone pad is flat and buttons are clear. The pink set is the Northern Electric version.  For some reason, they retained the rectangle around the keys and white buttons.  Note also that the number card is split, with half on either side of the "0" key. Production started in 1966. For models produced, go here: PRINCESS SETS
Touch Tone Trimline development timeline -- announced in 1967
Back to Rotary Trimline Development Timeline
	From a Bell System 1960 ad showing the concept for a Touch Tone "Pushbutton-In-Handset" phone based on the rotary dial-in-handset model that was in field trial at the time.
	2 models for the Touch Tone pushbutton-in-handset phone. The white one was named "Contour." Note the different handset widths to test grip comfort, the switch to round buttons and the addition of 2 extra buttons.  Curiously, the 0 key was on the left, not in the center. (Photo courtesy of Wayne Merit)
	Trimline, Contour and Pushbutton-In-Handset 3 competing 12-button designs from the Experimental Phones display (Courtesy of SBC Archives and History Center, San Antonio, Texas)
	Trimline Touch Tone -- as announced in 1967 Production handsets were marked 1220A inside the handset's back cover. Bases were stocked seperately and mated with handsets at installation time.  Installers could then mix and match to get a rotary or TouchTone handset with a desk or wall base.   AC1 - wall base (see rotary page)   AD1 - desk base (shown here) 10-button pad, round buttons. Returned to holes over the transmitter and receiver. Transmitter and receiver elements are replaceable. 5-conductor handset cords plug in to base and handset, so parts could be mated in the field during installation. Trials were held in 1964 in Chicago, IL.  200 sets.
Others
	1959 "Longfellow" design concept wood model. (Image courtesy of AT&T Archives and History Center, San Antonio.)
	Interesting concept from a 1960 ad.  I doubt that it was built at the time, but looks suspiciously familiar over 40 years later!
	1962 Call Director From a Bell System ca. 1962 brochure.
	1963 Video phone concept From a photo used in the October 1963 issue of Western Electric News Features. (Courtesy of Wayne Merit) For more on picturephones, go here:  WE Picturephones
	1964 Hospital Interphone Patient Set F 55903  1/64 10-button TouchTone Trimline Handset (rotary also available) Speakerphone for hands-free operation.  Privacy switch cuts off microphone. This model was for small hospitals.  Toll and Local switches select lines for outgoing calls.  The larger hospital models don't have these switches, as the PBX operator assigned outgoing lines. Also F 55873, without toll and local keys for larger hospitals.
	1965 Selective Dialer F56466  12-64 Keyset with integrated repertory dialer, 48 number capacity.  Buttons on upper left are change repertory and wait. Probably a step toward the touch-a-matic. (Image courtesy of AT&T Archives and History Center, San Antonio.)
	1966 Call-A-Matic keyset with integrated dialer. Remembers up to 500 numbers on magnetic tape, without the need for external cards as used in the 660 and 2660 series card dialers. (B&W scan courtesy of Wayne Merit)
	1966 1500 desk set with built-in phone directory. Not an automatic dialer.  Thumbwheel moves a paper directory.  Number must be manually dialed.  In field trial during summer 1966. (Scan courtesy of Wayne Merit) Wall Set with Directory From a Bell System publication 1966 2500 desk set with built-in phone directory. F-56731  10/66 Note the use of a G12 handset and Trimline-style handset cord.   (Courtesy of Lucent.)
	1966 Single button phone. Never a wrong number. Dials a pre-set number over the public network, such as a reservation or information hot-line. Planned for trial in 1966. (Scan courtesy of Wayne Merit)
	1968 Dial-In-Handset Uses integrated circuit technology. (Courtesy of SBC Archives and History Center, San Antonio, Texas) Also seen in a 1970 Bell System ad (below).
	1969 Keyset with LED display lights F-57628  2-69 G12 handset.  Number card holder also labeled "Push for recall" (Image courtesy of AT&T Archives and History Center, San Antonio.)
	1973 Touch-a-matic Prototype From Bell Labs News, 3/73 Anyone have an F-code or better photo?
	ca. 1974 Unmarked Accent prototype with Trimline handset and cord retractor. (Courtesy of Lucent.)
Other touch tone models are shown here: Experimental Phones Display Disneyland House of Tomorrow Display Western Electric Design Models Western Electric Picturephone Evolution	Continue to rotary models.