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3500-series Telephone Types

16-button dial sets including Autovon Sets

©2004-21 paulf.  All rights reserved.

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WE 3568

ON THIS PAGE:   Autovon Sets       Autovon Components       Non-WE Sets


The 3500 series was made from the mid-1960s thru the 1980s.

Sets were for use on the government's AUTOVON (AUTOmatic VOice Network) system, which connected sites worldwide.  It's key features include the ability to use 4-wire connections to minimize echo on long distance connections, the use of priority codes to give preference to higher priority communications when the system was operating at capacity, "hot line" dialing and conferencing.  A brief overview of the system may be found in "Bell Laboratories Record," April 1968.  An internet search on AUTOVON will provide more technical details and background information.

1.  FO -- Flash Override
2.    F --  Flash
3.    I -- Immediate
4.    P -- Priority
5.  (none)  -- Routine calls

The appropriate priority code was dialed with an "important" call, such as a command and control call.  If needed, calls starting with routine level and going up to the level below the dialed level were preempted.  The lower priority users got a tone sequence indicating their call was being preempted.

Standard 500 and 2500-series sets were used for routine callers, who did not have the need or authority to preempt other callers.  They may be found on other pages of this site (see links above).

BSPs for Autovon sets were moved from division 502 to division 529 when it was created for
"Station Apparatus and Equipment intended solely for specially-engineered lines, not for general telephone use."  This happened sometime before the publication of the 10/68 division 502 index.

This information is hard to find, as the BSPs and technical data were not generally distributed.
Later division indexes had a heart icon next to the BSPs, indicating:

"a new or reissued item which, because of its limited need, will not be distributed on standing order
except through coded distribution.
Additional copies may be obtained by placing regular (one-time) orders."

This page is intended to be a quick summary of the models produced and major functions.  Western catalogs and technical documentation only show the models that were in production or service at the publication date.  To understand the full scope of models produced we must compile data from many years of documents.

Each model had suffix letters that defined variations.
Details can be found in the Bell System technical documentation (e.g. BSPs - Bell System Practices).

Most info in the chart is from manufacturer catalogs and ads plus discussions on the ATCA and TCI listservs.  No claim is made regarding accuracy or completeness.

For more information, see my article "Top Secret Telephones,"
the cover story in the April 2011 issue of TCI's Singing Wires,
and search for Autovon in the TCI Library.

If you're enjoying looking at this level of detail and haven't joined one of the phone clubs yet, see the links page.

If you're identifying a phone, you still need to check the internal components as many phones were refurbed and had internal components changed or removed.  If done in a Bell System refurb facility, the code on the bottom was usually repainted or remarked.  Many independent shops or field mods were not remarked with the accurate model number.

When buying sets, watch out for standard phones that have been modified to look like Autovon sets, by replacing the dial and faceplate.  While these look like proper sets to the casual observer, closer scrutiny will generally show the lack of a ringer control on the left side (sets with N1A ringer), the required 4-wire circuitry inside and the proper markings on the bottom plate.

WE 3504 date    WE 3568 date

As with the 500 seeries, a W suffix indicates sets made without Bell System markings, and M indicates a Modular set.
More details on set coding are found on the 500-series page.

For color information, see: Phones in color!

This page is a work in progress.  Please send comments, additions and corrections.

Last update: 21 December 2021


Major Functions
(all are desk sets unless noted otherwise.)

3504 B/C
WE 3504
                    Single Line set
Single line desk set.  Factory wired for 4-wire service, but may be arranged for 2-wire service.

Equipped with a card-operated line switch, 66-series dial, N1A ringer, 425G network, exclusion switch, G3AR handset, polarity guard, D24E mounting cord.

3504B has opaque keys. 
3504C has translucent (illuminated) keys.
Wired for speakerphone use.
N1A ringer control is accessable on the left side of the housing.
    (I1, 11/66)

Apparatus Catalog, 1970,
p. 595

3568 HH/HT
WE 3568 keyset
6-button keyset.  66-series dial, N1A ringer, 425G network, exclusion switch, G3AR handset, polarity guard, D50W mounting cord.  MA4 relay for 2 or 4-wire operation.

3568HT has opaque keys. 
3568HH has translucent (illuminated) keys.
Wired for speakerphone use.
N1A ringer control is accessable on the left side of the housing.

WE3640 Call
Photo from Jim Stettler

WE 3641 Call Director,
Photo from Rick Walsh
Call Director.  66-series dial, T1A or N1A ringer, 4010B or 4228F network, exclusion switch, G3Y handset, polarity guard, D50W mounting cord.  MA4 relay for 2 or 4-wire operation.

3640 holds up to 18 buttons in 3 columns.
3641 holds up to 30 buttons in 5 columns.

Last letter A has opaque keys. 
Last letter B has translucent (illuminated) keys.

672A transmitter may be installed in the last module position for use with 3-type speakerphone.

3666 A1A/A1B
WE 3666 Dard
Photo from Wayne Merit
Card Dialer, 6-button keyset.  67-series dial, M1A ringer, 425G network, exclusion switch, G3AR handset, polarity guard, D50W mounting cord.  MA4 relay for 2 or 4-wire operation.

3666A1A has opaque keys. 
3666A1B has translucent (illuminated) keys.
Wired for speakerphone use.

Information on other Card Dialers -- WE Card Dialers
    (I1, 1/66)

WE 3756 panel phone
Photos from Rick Walsh

WE 3756
                  panel phone, back view
(Back view)
Panel phone

66A3C (2-77) dial has generic keycaps with clear plastic windows for insertion of application-specific legends on * and # keys and right column keys.

The set has a network, polarity guard, and a receive amplifier board.  It appears to be a 2-wire phone that generates the 16 tones.

Used in ESS test frames and possibly Autovon installations.

  - - - - - - -
From the Catalog Card dated 10-31-1979

Common battery, TOUCH-TONE® dial, 18-button illuminated panel-type key telephone set designed for flush mounting on a trunk test frame in a No. 2 ESS 2-wire office. Designed for use in No. 1A1 and 1A2 key telephone systems.

Equipped with a P-23F754, gray, metal face plate attached to the frame by means of magnetic catches and may be readily removed for maintenance purposes.

Hand Set: G3K-61
Color: Light gray
Dial: No. 66A3C
Cord Reel: 400444329
Pos. 1 Key No. 635Y5C
Pos. 2 Key No. 635C5C
Pos. 3 Key No. 635C5C
(r) In addition to the apparatus listed, set also contains a No. 4228T network, No. 241A amplifier, No. 186A network, KS-8110 L2 buzzer, a polarity guard assembly, a line switch assembly, and a cable assembly.

The spring combinations associated with the six pushbuttons of the No. 635Y5C key provide a HOLD (Red), a RELEASE(Green), a FLASH (Amber) , and three line PICKUPS (Clear) which are convertible for signaling.

The spring combinations associated with the six pushbuttons of the No. 635C5C keys provide six line pickups on each key withall pickups convertible for signaling.

All pickup key buttons are each illuminated with a No. 61A lamp and serve as line busy, held line, and/or incoming call signals. Interchangeability of any line pickup to any pickup button on each key is provided by plug-in connectors on the back of the key frame.

A No. 251D terminal strip provides gun-wrapped type terminals for all external connections to the set.

Arranged for mounting but not equipped with a D-180387 kit of parts (ordered separately when required) which provides an electromagnetic transmitter, a loud speaker, a 3-stage transistor-type amplifier, a key and volume control unit, and a special face plate for use in the 3 type speakerphone system. Also arranged so that an operator head telephone set may be switched into the telephone circuit by external switching relays.

Initial use: On Trunk Test Frame No. 2 ESS 2-Wire Office.

 WE Catalog Card


WE 1008 adjunct for AUTOVON      Autovon Adjuncts

Model Major Functions BSP
type dials
16-button dials with Autovon-specific keys: "star," A, FO, F, I and P.

Available with opaque or translucent (lighted) keys.  (Photo above right.)
type dials
Card Dialer with 16-button dial with Autovon-specific keys: "star," A, FO, F, I and P.
Adjunct with rotary dial, for addition to AUTOVON sets.  (Photo above left.)
Used when an AUTOVON set user dialed out to a line that supported only rotary dialing.
Adjunct with AUTOVON dial. (Photo above right.)

Information on this page is from BSP and catalog data provided by Dave Gruger and Wayne Merit and from my collection.

WE 3568 keyset
U.S. Army TA-814/G Secure Phone    

Modified 3568HT AUTOVON set with Roanwell Confidencer handset.


May be documented in TM 11-5805-570-15 (NAVELEX 0967-291-5013, TO 31W2-2G-71)
Operator's, Organizational, Direct Support, General Support and Depot Maintenance Manual for Telephone Set TA-814/G.

Please let me know if you have or find a copy.
TA-814/G bottom

Automatic Electric Autovon Set
Automatic Electric Autovon Set

Built in the same housing as the AE880 speakerphones and similar products.

  See:  speakae.htm
AE Autovon
Automatic Electric Autovon Adjunct

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©2007-21 paulf.  All rights reserved.