Old Number 4 Crossbar (#4XB) Tandem List

 

A chronological date of installation and location listing of #4 Crossbar Toll Switches (#4XB) used in the North American toll network from the 1940s through the 1980s.

This list was compiled by telephone historian Mark Cuccia of New Orleans, LA USA .


Listen to Mark explain the history of Number 4 crossbar switches
(3 min 36 sec).
(Source: Phone Trips website)

Streaming MP3 file or Regular MP3 file

 

History of the Number 4 Crossbar (#4XB) Tandem Switch
& listing of former #4XB switches

The following is a chronological listing of date of installation and location of Western Electric/Northern Electric/North Electric #4 Crossbar Toll Switches.
This is a summary of the #4-type Crossbar (XB) Toll machine's history.
The Bell System started introducing them in the 1940's to prepare for
the semi-automated "Nationwide Operator Toll Dialing" introduced in the
late 1940s, and for ultimate (fully-automated) customer-dialed 'DDD'
(Direct Distance Dialing) introduced throughout the 1950's and 60's.

There are two specific important individuals from Bell Telephone
Laboratories who were very much involved in the continuing development
of new and improved innovations for the #4-type XB Toll machine:
Amos E. Joel, Bell Labs (1941-84), retired;
and the recently deceased Robert J. Keevers, Bell Labs (1957-83) ->
 Bellcore (1984-92).

In the charts/lists below:

- the first column is the date of installation -

- the second column is the CLLI (Common Language Location Identifier)
of the switch. [NOTE: CLLI was developed by Bell Labs in the late 1960s
and began to be used by AT&T Long Lines and the Operating Companies
through the 1970s. With divestiture, management of the CLLI code
assignments went with Bellcore (now Telcordia) Language Standards;
ALSO, it _IS_POSSIBLE_ that a CLLI code used at one time for a switch
that has been retired _COULD_ be re-used for a new switch]

- the third column is the "rank" or "classification" of the switch
within the DDD network hierarchy, _AS_OF_ the 1976 timeframe. The
switch listed may have been 'higher' or 'lower' within the network
hierarchy prior to 1976, as well as after 1976 (before its retirement).

[Other types of switch-equipment, such as XB-Tandem, #5-type XB, and
 SXS (Step-by-Step), could be used for Toll/Tandem functions within the
 DDD Network in the US and Canada].

[Class-1 switches are "Regional"-
there were twelve regionals within the DDD Network, the one not in any
of the below lists/charts is that of Regina 1 SK, REGNSK0101T, which
was a XB-Tandem (NOT a #4-type XB) installed in Nov 1955;
 Class-2 switches are "Sectional", more numerous than "Regionals";
 Class-3 switches are "Primary", more numerous than "Sectionals";
 Class-4 switches are "ordinary toll switches", most numerous;
 One particular #4A machine (Dallas-Taylor LOCAL, DLLSTXTA02T) was
STRICTLY used as a local-area tandem and is shown as 'L' for its
hierarchical class/rank in the network].

- the fourth column is the "recorded announcement trailer" that was
given by recorded announcements from that #4-type XB machine, again
_AS_OF_ the 1976 timeframe. As with the previous column indicating the
switch's class/rank within the network, the "trailer" digits may have
changed as a particular switch may have moved 'up' or 'down' in the
network hierarchy over the years. Also, as with the CLLI-codes, the use
of recorded announcements trailers that quote the NPA-code followed by
one-or-two digits was _NOT_ used until the late-1960's. Prior to that,
the city-name (and sequence digit) was quoted at the end of recorded
announcements, although there ALSO was an alpha-numeric coded trailer
format used as well prior to the NPA-digit(s) trailers.

[There were specific rules/guidelines that AT&T had for assignments of
the digit(s) after the NPA as used in the "trailers":
If the switch were a Cl.1 (Regional), the digit following the NPA would
be a '1'. If the switch were a Cl.2 (Sectional), the digit following
the NPA would be a '2' (and if there were two Cl.2 offices in that NPA
region, the second Cl.2 toll office would use a '3' in its trailer
digits). If the switch were a Cl.3 (Primary) or a Cl.4 ('ordinary' toll
office), the additional digit(s) after the NPA code in the 'trailer'
would be a '4' or above. There were a few deviations from this "rule",
but for the most part, it was followed. Also, it didn't really matter
what type of 'equipment' the toll or tandem switch had for the trailer
digit(s) - all that mattered was the NPA the switch was located in and
the switch's "rank" in the network's hierarchy. Also, the NPA's digits
listed here as quoted in the trailer may not necessarily have been the
actual NPA at the time of switch installation, nor during continued
service of the switch, due to various NPA-splits throughout 1950's,
the 1965 FL 305/904 split, and the 1973 VA 703/804 split, or any of the
1980's/early-90's era NPA-splits. As new #4ESS switches completely
retired/replaced a #4-type XB switch, the same "trailer" was usually
reassigned to be used by that #4ESS switch.]

- the fifth column is the city-name and sequence number of the switch.
This was what was quoted in recorded announcement trailers prior to the
late 1960's, as well as the only way the switch was named/listed in any
telco documentation prior to the introduction of CLLI-codes in the late
1960's or early 1970's.

- finally, if the #4-type XB Toll switch were in Canada, Hawaii, or
for an independent (non-Bell) telco within the continental US, that too
is specifically noted.

[Also, there are two specific instances of an _AT&T_Long_Lines_ owned/
operated #4A XB Toll switch being physically-located within non-Bell
(independent) territory. Both switches were Class-1 Regionals, one at
San Bernardino CA and the other at Norway IL. Additionally, the local
independent telco for _BOTH_ of these locations is GTE. San Bernardino
CA _IS_ the name of the GTE-ratecenter; Norway is a 'locality' within
the Sheridan IL GTE-ratecenter. These two #4As are _NOT_ noted in the
lists below as "independent", since they were OWNED by AT&T, and NOT
GTE, even though they were physically located within GTE's territory.

Now, as for the chronological lists and additional notes:

Listed below are the first six #4-XB Toll machines. WECO manufactured
and installed them for service without any 'Card-Translator' Boxes.
Actually, the Card Translator hadn't even been invented/developed at
the time (1943). However, by 1949 the Card-Translator was already under
development by WECO/Bell-Labs. When the Card-Translator was perfected
by 1953, these six original #4-XB Toll machines were MODIFIED for the
addition of Card-Translators, and were thus re-named #4M machines, the
'M' for Modified. Unfortunately, I don't have the dates that these
machines were modified for card-translators, other than that it was
during/after 1953.

The very first #4-XB machine installed in 1943 in Philadelphia was the
_ONLY_ #4-type XB Toll machine which had a special new "cord-LESS"
Operator Position Board (#4-Board) for most inward, thru-calling, and
tandem operator functions. There were also the usual cord/plug/jack
operator toll boards associated with this #4XB, including a _NEW_ #5
Board with paired/double cords/plugs/jacks (each paired cord/plug/jack
had the usual three metal contacts: tip/ring/sleeve) for full '4-wire
trunk' connections. The #5 Board was used for "delayed" calls. The new
(only) #4 cord-LESS Operator Board/Position was modeled after earlier
cord-less "Operator Panel" boards used in some metro areas which had a
lot of 'Panel' local switching. And, this 'style' of cord-less board
was also a predecessor for later CAMA/PPCS/TSP/TSPS cord-less operator
positions/boards. I don't know if/when the #4-type cord-less board was
ever removed from service in favor of "usual" #3-type toll cord-boards
(such as later in the 1950's?), but the #5 "delayed-call" board with
its double/paird plugs/cords/jacks was used at many International
Gateway Operator boards/positions in the 1960's.

Also, the #4-type XB Toll machine had been under development in the
late 1930's and very early 1940's, before the U.S. became involved in
WW-II. While the U.S. had recently entered 'The War' by 1943, the
#4 machine developed for Philadelphia was installed. However, no
further #4 machines were installed until 1948, a few years after WW-II
was over.

Even though the Area Code (NPA) format wasn't 'finalized' until October
1947, and most toll calls were still completely manually handled on a
cordboard by an operator, there had been several regional SxS Operator
Toll Dial networks in the US and Canada dating back to the 1920s (and
even the 'teens'), as well as a few regional Panel/#1XB Operator Toll
Dial networks. These regional Operator toll dial networks were merged
into the Nationwide Operator Toll Dial network. And Operators had been
routing toll calls by dialing/keying 0XX/1XX operator codes on those
regional Operator Toll Dial networks since they began, and still use
such 0XX/1XX codes for operator/network internal functions to this day.

Aug 1943 PHLAPAMK41T 3 215-2 Philadelphia 2 PA (pre-1976 was Cl.2)

Nov 1948 NYCMNYAA02T 2 212-2 New York 4 NY
Dec 1948 CHCGILCG42T 3 312-8 Chicago 2 IL (pre-1976 Cl.2 312-2)
June 1949 CLEVOH6201T 3 216-15 Cleveland 1 OH
Oct 1949 OKLDCA0341T 2 415-2 Oakland 3 (Franklin) CA
Nov 1949 BSTNMAFR02T 2 617-2 Boston 2 MA


These thirteen machines were originally called #A4A machines. This
stood for "Anticipated" #4 "Advanced". They were originally installed
withOUT any card-translator boxes, however they were manufactured for
"easy" addition of card-translators when they became perfected for use
in 1953. Unfortunately, I don't have the dates that these machines
added their card-translators, other than that it was during/after 1953.

Apr 1950 ALBYNYSS04T 2 518-2 Albany 2 NY
July 1950 IPLSIN0104T 2 317-2 Indianapolis 1 IN
Aug 1950 BLTMMDDT02T 2 301-2 Baltimore 2 MD
Sept 1950 WASHDCDT04T 3 202-4 Washington 1 DC
Nov 1950 KSCYMO0914T 2 816-2 Kansas City 1 MO
Feb 1951 MPLSMNDT04T 2 612-2 Minneapolis 1 MN
July 1951 PITBPADT41T 2 412-2 Pittsburgh 1 PA
Oct 1951 ATLNGATL42T 2 404-2 Atlanta 1 GA
Nov 1951 DLLSTXTL14T 1 214-1 Dallas 1 TX
Feb 1952 OMAHNENW04T 2 402-2 Omaha 1 NE
July 1952 HSTNTX0114T 2 713-2 Houston 1 TX
Sept 1952 CNCNOHWS04T 2 513-2 Cincinnati 1 OH
Mar 1953 NWORLAMA01T 2 504-2 New Orleans 1 LA

The Card-Translator was a separate peripheral, a box of up to 1000
large metal punched cards. The arrangement of the punched holes on a
particular card would correspond to a particular routing code that the
#4A/4M machine would request from the Card-Translator. A 'light-source'
would project through the specific punched holes on that card, and
a 'photo-cell' would pick-up the particular light that passed through
those punched holes. That information would be returned back to the
#4A/4M machine as routing (and alternate route) instructions for the
machine to continue to switch/route the call to its ultimate location.
Prior to the introduction of the Card-Translator, the original #4 and
initial working of #A4A machines did their routings translations from
hard-coded instructions within the machine itself.

All of these machines were manufactured and installed as #4A XB Toll
machines - the 'A' standing for "Advanced" - meaning that the switches
were installed with their card-translator boxes.

May 1953 SCTNPASC41T 3 717-4 Scranton PA
June 1953 SCRMCA0121T 1 916-1 Sacramento 1 CA
Aug 1953 NWRKNJ0205T 2 201-2 Newark 2 NJ
Oct 1953 DTRTMIBA40T 2 313-2 Detroit 1 MI
Feb 1954 OKCYOKCE14T 2 405-2 Oklahoma City 1 OK
May 1954 LSANCA0201T 2 213-2 Los Angeles 2 CA
May 1954 LTRKARFR14T 3 501-4 Little Rock AR
May 1954 SYRCNYSU04T 3 315-4 Syracuse NY
June 1954 RCMDVAGR01T 2 804-2 Richmond 1 VA
Sept 1954 CHCGILEG43T 3 312-16 Chicago 3 IL (pre-1976 Cl.2 312-3)
Nov 1954 WHPLNY0201T 1 914-1 White Plains 2 NY
Nov 1954 CHRLNCCA01T 2 704-2 Charlotte 1 NC
Nov 1954 DNVRCOMA01T 2 303-2 Denver 1 CO
Apr 1955 STLSMO0914T 1 314-1 St.Louis 1 MO
May 1955 MILWWI4841T 3 414-11 Milwaukee 1 WI
June 1955 TOROON0101T 2 416-2 Toronto 1 ON [CAN:Bell Canada]
Aug 1955 SNANTXCA04T 2 512-2 San Antonio TX
Nov 1955 PTLDOR6201T 2 503-2 Portland 1 OR
Dec 1955 HRBGPAHA41T 2 717-2 Harrisburg PA
Dec 1955 JCVLFLCL01T 2 904-2 Jacksonville 1 FL
May 1956 MTRLPQ0201T 1 514-1 Montreal 1 PQ [CAN:Bell Canada]
May 1956 BFLONYFR04T 3 716-4 Buffalo 1 NY
Oct 1956 CLMBOH1102T 3 614-4 Columbus 2 OH
Oct 1956 MMPHTNMA41T 2 901-2 Memphis 1 TN
Oct 1956 NSVLTNMT41T 2 615-2 Nashville 1 TN
Apr 1957 TUSLOKTB14T 3 918-4 Tulsa OK
May 1957 WAYNPALA41T 1 215-1 Wayne 1 PA
June 1957 DESMIADT04T 2 515-2 Des Moines IA
Aug 1957 BRHMALMT56T 2 205-2 Birmingham 1 AL
Oct 1957 SNBRCA0133T 1 714-1 San Bernardino CA
Oct 1957 WCHTKSBR14T 3 316-4 Wichita KS
Nov 1957 MIAMFLTL02T 4 305-5 Miami 2 FL
Nov 1957 LSVLKYCS04T 2 502-2 Louisville 1 KY
Mar 1958 SLKCUTMA01T 2 801-2 Salt Lake City 1 UT
June 1958 SNJSCA0203T 2 408-2 San Jose 1 CA
Jan 1959 STTLWA0101T 2 206-2 Seattle 1 WA
Apr 1959 CLMASCTL01T 2 803-2 Columbia 1 SC
June 1959 JCSNMSPS04T 2 601-2 Jackson 2 MS
Apr 1960 ALBQNMMA01T 2 505-2 Albuquerque 1 NM
June 1960 RCDLGATL41T 1 404-1 Rockdale GA (Conyers)
July 1960 FTWOTXED14T 2 817-2 Ft.Worth TX
Aug 1960 GNBONCEU01T 2 919-2 Greensboro 1 NC
Sept 1960 SPFDILSF41T 2 217-2 Springfield 1 IL
Feb 1961 KNVLTNMA41T 3 615-4 Knoxville 1 TN
Mar 1961 CHTNWVLE24T 2 304-2 Charleston 1 WV
Aug 1961 TOLDOH2101T 3 419-4 Toledo OH
Mar 1962 LSANCA0307T 3 213-4 Los Angeles 3 CA
Apr 1962 SPKNWA0101T 3 509-4 Spokane WA
Nov 1962 ORLDFLMA01T 2 305-2 Orlando 1 FL
Dec 1962 NRWYILNO41T 1 815-1 Norway 1 IL
May 1963 SPFDMABR01T 2 413-2 Springfield 2 MA
Sept 1963 NYCMNY5404T 2 212-3 New York 7 NY
Nov 1963 DYTNOH1501T 3 513-4 Dayton OH
Dec 1964 ANHMCA0128T 2 714-2 Anaheim 1 CA
Feb 1965 WNPGMB0101T 2 204-2 Winnipeg MB [CAN:MTS]
Nov 1966 RCPKNJ0201T 3 201-4 Rochelle Park 1 NJ
Dec 1966 PHNXAZMA01T 2 602-2 Phoenix 1 AZ
Mar 1967 WASHDCSW04T 2 202-2 Washington 3 DC
Mar 1967 SNDGCA0288T 2 714-3 San Diego 1 CA
May 1968 NWHNCT0203T 2 203-2 New Haven 4 CT


Beginning in April 1969, the first #4A-ETS XB machines were installed,
using an Electronic Translator System instead of Card-Translator
boxes. However, not all of the below machines installed during the
1969-71 time-frame had ETS at installation. Some of them still had
Card-Translator boxes. Those were San Francisco 1 CA, Fort Wayne IN,
Tampa 2 FL, Eau Claire 1 WI, Saskatoon SK, and Halifax 1 NS.
The San Francisco 1 CA did have an ETS replace its Card-Translator in
Jan 1972. The others might not have become ETS by the time they were
retired. Also, most of the earlier (pre-1969) #4A machines ultimately
had their Card-Translators replaced by ETS before the time the machines
were retired but NOT ALL of them became ETS before retirement.

Apr 1969 GDRPMIBL40T 2 616-2 Grand Rapids 1 MI
June 1969 SNFCCA0141T 3 415-15 San Francisco 1 CA
June 1969 FTWYINXA04T 4 219-5 Ft.Wayne IN [INDP:GTE]
July 1969 PLMOMIFA40T 3 313-11 Plymouth 1 MI
Aug 1969 PUBLCOMA01T 3 303-5 Pueblo 1 CO
Aug 1969 TAMPFLXA02T 3 813-4 Tampa 2 FL [INDP:GTE]
Oct 1969 CMDNNJCE02T 2 609-2 Camden 2 NJ
Feb 1970 DLLSTXTA02T L ----- Dallas (Taylor) TX LOCAL
Feb 1970 RDCYCA0242T 3 415-16 Redwood City CA
Apr 1970 BSTNMAFR09T 2 617-3 Boston 9 MA
Apr 1970 SBNDIN0504T 2 219-2 South Bend 1 IN
May 1970 SLTSMO0924T 2 314-2 St.Louis 2 MO
May 1970 EUCLWI0141T 2 715-2 Eau Claire 1 WI
June 1970 HNTNNYSU01T 2 516-2 Suffolk 1 NY (Huntington)
Aug 1970 BLTNIN0104T 2 812-2 Bloomington 1 IN
Aug 1970 NBWKNJNB02T 3 201-19 New Brunswick 4 NJ
Sept 1970 SKTNSK0102T 3 306-4 Saskatoon SK [CAN: SaskTel]
Nov 1970 PITBPADG42T 1 412-1 Pittsburgh 2 PA
Apr 1971 SHOKCA0263T 3 213-15 Sherman Oaks 2 CA
Apr 1971 HLFXNS0101T 3 902-4 Halifax 1 NS [CAN: Bell's MT&T]
Apr 1971 VANCBC0104T 2 604-2 Vancouver 2 BC [CAN: GTE's BCTel]
June 1971 CHCGILCL46T 2 312-2 Chicago 6 IL (pre-1976 Cl.3 312-8)
June 1971 HSTNTX0124T 3 713-6 Houston 2 TX
June 1971 CLSPCOMA01T 3 303-7 Colorado Spr. 1 CO
July 1971 DLLSTXTL14T 2 214-2 Dallas 2 TX
Aug 1971 BTRGLAMA01T 4 504-6 Baton Rouge 1 LA
Aug 1971 RLGHNCMO03T 3 919-5 Raleigh NC
Nov 1971 STPLMNMK04T 3 612-5 St.Paul 2 MN
Nov 1971 CLMBGAMT42T 4 404-5 Columbus 1 GA
Nov 1971 SPBGFLXA02T 4 813-9 St.Petersburg FL [INDP:GTE]
Dec 1971 NYCMNYVS01T 4 212-45 New York (Varick St.) NY
Jan 1972 HNLLHIZA01T 3 808-4 Honolulu HI [INDP:GTE-Hawaiian Tel]
Feb 1972 ARTNVACK03T 3 703-10 Arlington 2 VA
Mar 1972 EDTNAB0201T 3 403-5 Edmonton AB [CAN:AGT]
Apr 1972 EVRTWAXA01T 3 206-9 Everett 1 WA [INDP:GTE]
Apr 1972 FLRNSCMA02T 3 803-6 Florence SC
Apr 1972 MSSNKSFR04T 3 913-5 Mission KS
May 1972 NRFLVABS02T 3 804-8 Norfolk 3 VA
May 1972 FYVLNCXA02T 3 919-7 Fayetteville NC [INDP:UnitedCarolina]
May 1972 CHYNWYMA01T 2 307-2 Cheyenne 1 WY
June 1972 DNVRCOMA03T 1 303-1 Denver 3 CO
June 1972 PRVDRIGR04T 3 401-6 Providence 4 RI
June 1972 FTWSPAFW41T 3 215-12 Ft.Washington 1 PA
June 1972 PNTCMIFA40T 3 313-12 Pontiac 2 MI
June 1972 FRSNCA0144T 3 209-6 Fresno 2 CA
Aug 1972 NYCMNY5405T 3 212-49 New York 6 NY
Aug 1972 CLEVOH0202T 3 216-15 Cleveland 2 OH
Aug 1972 OKBRILOA41T 4 312-12 Oak Brook IL
Nov 1972 LSVGNVXB04T 4 702-5 Las Vegas 1 NV [INDP:Centel]
Nov 1972 CLWRFLXA02T 4 813-0 Clearwater FL [INDP:GTE]
Nov 1972 TOROON1103T 4 416-6 Toronto 3 ON [CAN:Bell Canada]
Nov 1972 OJUSFLTL02T 3 305-9 Ojus 1 FL
Nov 1972 CHMPILRA41T 3 217-4 Champaign 1 IL
Jan 1973 ATLNGANW43T 3 404-6 Atlanta 3 GA
Mar 1973 LGVWTXTL14T 3 214-5 Longview TX
Mar 1973 HYWRCA0246T 3 415-17 Hayward CA
Apr 1973 OTWAON1002T 3 613-5 Ottawa 2 ON [CAN:Bell Canada]
May 1973 PNSCFLBL03T 4 904-6 Pensacola FL
May 1973 WKSHWI0241T 2 414-3 Waukesha 2, WI
May 1973 GRDNCA0221T 3 213-6 Gardena 1 CA
May 1973 RENONV0304T 2 702-2 Reno 3 NV
June 1973 NYCMNYBW01T 3 212-10 New York 10 NY
June 1973 CMBRMABE16T 3 617-16 Cambridge 16 MA (Kendall Sq.)
June 1973 PTLDMEFO02T 3 207-7 Portland 2 ME
June 1973 OKLDCA0342T 3 415-9 Oakland 5 (Franklin) CA
July 1973 NWRKNJ0205T 3 201-20 Newark 7 NJ
Oct 1973 WHPLNYWP03T 3 914-11 White Plains 4 NY
Oct 1973 HRFRCT0304T 3 203-5 Hartford 3 CT
Oct 1973 PEORILPJ41T 3 309-4 Peoria 2 IL
Oct 1973 GRCYNYGC01T 4 516-10 Garden City 1 NY
Oct 1973 LWRNMACA02T 3 617-29 Lawrence 2 MA
Oct 1973 CRCHTXTU04T 3 512-8 Corpus Christi 1 TX
Nov 1973 AKRNOH2502T 3 216-16 Akron 2 OH
Feb 1974 NYCMNYBW20T 4 212-20 New York (Broadway 2) NY
Mar 1974 DTRTMIBH40T 4 313-6 Detroit 2 MI
Mar 1974 SNFCCA2142T 4 415-18 San Francisco 2 (Folsom) CA
Apr 1974 DNVRCOZJ04T 4 303-6 Denver 4 CO
Apr 1974 RCMTNCXA02T 3 919-9 Rocky Mt. 2 NC [INDP:UnitedCarolina]
Apr 1974 DCTRALMT56T 3 205-6 Decatur 1 AL
Apr 1974 SHPTLATL02T 3 318-5 Shreveport 1 LA
Apr 1974 NBRKILNT41T 3 312-14 Northbrook 2 IL
Apr 1974 PTLDOR6202T 3 503-3 Portland 2 OR
Apr 1974 SKTNCA0110T 2 209-2 Stockton 2 CA
Apr 1974 STTLWA0602T 3 206-8 Seattle 2 WA
May 1974 BLTMMDDT02T 3 301-9 Baltimore 9 MD
May 1974 AUSTTXGR04T 3 512-6 Austin 1 TX
May 1974 ANHMCA0177T 3 714-7 Anaheim 2 CA
June 1974 PHLAPASL41T 3 215-14 Philadelphia 3 PA
June 1974 FRMNMAWA03T 3 617-27 Framingham MA
June 1974 CDKNNJCK01T 3 201-22 Cedar Knolls 1 NJ
June 1974 SHOKCA0373T 4 213-73 Sherman Oaks 3 CA
June 1974 KLMZMIFA40T 3 616-5 Kalamazoo 2 MI
June 1974 TCSNAZMA02T 3 602-4 Tucson 2 AZ
Aug 1974 NYCMNYBW02T 3 212-12 New York 11 NY
Aug 1974 GSVLFLAN03T 3 904-7 Gainesville 2 FL
Oct 1974 SRSTFLXF01T 4 813-6 Sarasota 3 FL [INDP:GTE]
Oct 1974 HMSQNJHS01T 3 609-7 Hamilton Sq. 1 NJ
Dec 1974 SGNWMIFA40T 3 517-5 Saginaw 2 MI
Feb 1975 BOISIDMA02T 3 208-4 Boise 2 ID
Mar 1975 HSTNTX0834T 4 713-7 Houston 3 TX
Mar 1975 BRTNMACO02T 3 617-22 Brockton 2 MA
Mar 1975 SNTCCA0120T 2 408-3 Santa Clara CA
Apr 1975 BRPTCT0403T 3 203-15 Bridgeport 4 CT
Apr 1975 GSTANCSO02T 3 704-5 Gastonia NC
Apr 1975 YNTWOH0202T 3 216-21 Youngstown 2 OH
Apr 1975 GRELCOJC01T 3 303-10 Greeley 1 CO
May 1975 RONKVALK02T 3 703-8 Roanoke VA
May 1975 WNSLNCFI02T 3 919-4 Winston-Salem NC
May 1975 MACNGAGA42T 2 912-2 Macon 2 GA
May 1975 GRDNCA0231T 4 213-31 Gardena 2 CA
May 1975 SNRSCA0236T 2 707-2 Santa Rosa 2 CA
June 1975 RCPKNJ0202T 4 201-23 Rochelle Park 2 NJ
June 1975 GNVLSCTL01T 3 803-4 Greenville SC
June 1975 LNNGMIMN40T 3 517-4 Lansing 2 MI
July 1975 WLMGDEWL41T 3 302-7 Wilmington DE
Sept 1975 WRCSMA0202T 3 617-31 Worcester 2 MA
Sept 1975 WPBHFLAN03T 3 305-10 West Palm Beach 3 FL
Oct 1975 TAMPFLXA03T 4 813-11 Tampa 3 FL [INDP:GTE]
Oct 1975 COVLILCL41T 2 618-2 Collinsville 2 IL
Oct 1975 MESAAZMA01T 4 602-4 Mesa AZ
Nov 1975 OJUSFLTL02T 4 305-11 Ojus 2 FL
Nov 1975 FARGNDBC03T 2 701-2 Fargo 1 ND
May 1976 MDSNWI0241T 3 608-2 Madison 2 WI (to become Cl.2 later?)


CCIS(6), Common-Channel Interoffice-Signaling began to replace the
MF (Multi-Frequency) keypulse signaling between #4A offices starting
in 1976. However, NOT ALL #4A machines were modified for CCIS by the
time of their retirement. Some #4-type machines NOT modified for CCIS
were using their ETS as a CCIS-STP (Signal Transfer Point) for _OTHER_
CCIS-enabled switches elsewhere in the DDD Network.

The VERY FIRST #4ESS toll switch, CHCGILCL57T, Chicago 7 IL (initially
classed/ranked as a High Volume SRT- Selective Routing Tandem, 312-10;
later reclassed as a Cl.2/SRT, 312-2) was installed in Jan 1976, BEFORE
the last #4A-ETS XB toll switch, MDSNWI0241T, 608-2, Madison 2 WI was
installed in May 1976. The use of new #4ESS toll switches replaced
(retired) the older #4A/4M XB toll switches, starting in late-1976,
and continuing through the late-1980s / early-1990s.

As of 1-Jan-1984, the "Bell System" was broken up - the Divestiture of
AT&T. Of the remaining (US) Bell System location #4A/4M XBs still in
service as of 1984, most were kept under AT&T, while some were turned
over to the local Bell Operating Companies.

Also, by the mid-1980's, the "rank" or "classification" of the toll
switch by "hierarchy" (Class-1 Regional, Class-2 Sectional, etc) had
become 'meaningless', as a new technology called DNHR: Dynamic
Non-Hierarchical Routing was introduced into the network.

As #4ESS offices were installed by AT&T (and the Bell Operating Co's)
and other new digital switches were installed by the BOCs (particularly
DMS-200s), the last remaining #4-type XB toll machines were retired by
the late 1980's or early 1990's.

There were a total of 202 #4-Type XB Toll Machines installed in the
DDD Network - and during most of 1976, ALL were in actual use:

182 US Bell System
4 Bell Canada (PQ/ON)
5 other Canada TCTS (GTE-BC; AB; SK; MB; Bell's MT&T in Halifax NS)
 10 independent telcos in continental US
(GTE- 5 in the Tampa Bay metro area in Florida,
and 1 each in Everett WA and Fort Wayne IN;
United's Carolina Tel & Tel- 2 in NC: Fayetteville, Rocky Mount;
Centel- 1 for Las Vegas NV)
1 Hawaii (GTE-Hawaiian Telephone Co)
---
202 TOTAL of #4-type XB's


To summarize the _NON_ "US-Bell System" #4As:

Bell Canada:
June 1955 TOROON0101T Toronto 1 ON
May 1956 MTRLPQ0201T Montreal 1 PQ
Nov 1972 TOROON1103T Toronto 3 ON
Apr 1973 OTWAON1002T Ottawa 2 ON

Other TCTS in Canada:
Feb 1965 WNPGMB0101T Winnipeg MB [MTS]
Sept 1970 SKTNSK0102T Saskatoon SK [SaskTel]
Apr 1971 HLFXNS0101T Halifax 1 NS [Bell's MT&T]
Apr 1971 VANCBC0104T Vancouver 2 BC [GTE's BCTel]
Mar 1972 EDTNAB0201T Edmonton AB [AGT]

HAWAII:
Jan 1972 HNLLHIZA01T Honolulu HI [GTE-Hawaiian Telephone Co]

other independents:
June 1969 FTWYINXA04T Fort Wayne IN [GTE]
Aug 1969 TAMPFLXA02T Tampa 2 FL [GTE - FL]
Nov 1971 SPBGFLXA02T St. Petersburg FL [GTE - FL]
Apr 1972 EVRTWAXA01T Everett 1 WA [GTE]
May 1972 FYVLNCXA02T Fayetteville NC [United- Carolina Tel & Tel]
Nov 1972 LSVGNVXB04T Las Vegas 1 NV [Centel]
Nov 1972 CLWRFLXA02T Clearwater FL [GTE - FL]
Apr 1974 RCMTNCXA02T Rocky Mount 2 NC [United- Carolina Tel & Tel]
Oct 1974 SRSTFLXF01T Sarasota 3 FL [GTE - FL]
Oct 1975 TAMPFLXA03T Tampa 3 FL [GTE - FL]


In addition to all of the 202 above listed #4A/4M XB Toll machines,
there were four small #4AXB's installed in Alaska during the 1960s
and/or 1970's. These were primarily for Government/Military/Autovon
use, but also connected the Alaskan Autovon/Military network with the
'commercial' AT&T/Bell-System network in North America...

Anchorage AK
Fairbanks AK
Pedro Dome AK
Kalicacket Creek AK

There were also at least twelve 'ETS-4' switches manufactured by the
North Electric Company of Galion OH (not to be confused with Canada's
Northern Electric Company - now known as Northern Telecom or Nortel -
which when it was still known as Northern Electric was partially held
by AT&T and Western Electric, in addition to being part of Bell Canada
which in itself was partially held by AT&T). These ETS-4 switches _MAY_
have had some similarities to WECO/NECO's #4A-ETS XB Toll switch, at
least as far as their relation with the rest of the DDD network. The
'internal' aspects of the ETS-4 weren't 'identical' to the internal
aspects of the #4A, however. During the 1970's and early 1980's, they
were used in the following independent GTE and United Tel locations.
All were Class-4, except for the GTE location of Ontario CALIFORNIA
which was a Class-3.

YORKPAXP49T 4 717-9 York PA [GTE]
ERIEPAXH41T 4 814-5 Erie PA [GTE]
WRRNOHXA01T 4 216-17 Warren OH [United Tel]
LIMAOHXA51T 4 419-7 Lima OH [United Tel]
ALMAMIXG12T 4 517-9 Alma MI [GTE]
MSKGMIXK12T 4 616-8 Muskegon MI [GTE]
LXTNKYXA06T 4 606-7 Lexington KY [GTE]
JHCYTNXC41T 4 615-7 Johnson City TN [United's Inter-Mountain Tel]
FTMYFLXA03T 4 813-5 Fort Myers FL [United Tel - FL]
ONTRCAXP91T 3 714-8 Ontario CA [GTE]
LNBHCAXP40T 4 213-40 Long Beach CA [GTE]
SNMNCAXP41T 4 213-41 Santa Monica CA [GTE]

Incidentally, Galion OH (the location of the North Electric Company
which manufactured the ETS-4 switch) is a ratecenter served by GTE,
and that ratecenter is part of United Tel's Lima-Mansfield OH LATA!

The #4-type XB Toll switch served the Bell System / North American
DDD Network in the US and Canada in one-way-or-another for nearly
half-a-century. It was frequently going through various upgrades,
improvements and innovations during its life. One thing that was added
to the capability of the #4-type XB Toll switch was the ability to act
as an International/Overseas Gateway switch. In the 1960's and 70's the
following #4A/4M XB switches did handle international/overseas gateway
traffic: New York 4 NY [4M], Springfield 2 MA (which was later handled
by New York 10 NY), White Plains 2 NY, Pittsburgh 2 PA, Miami 2 FL
(which was later handled by Jacksonville 2 FL), Oakland 3 CA [4M],
Denver 3 CO, Montreal 1 PQ, Vancouver 2 BC, and Toronto 1 ON.
[NOTE Re, Canada: the Bell Canada Montreal 1 PQ 4A Gateway and the
BC-Tel Vancouver 2 4A Gateway each actually routed on dedicated trunks
into COTC/Teleglobe's "Ericsson" XB Gateways, one each in Montreal and
Vancouver; Bell Canada's Toronto 1 ON 4A Gateway actually routed on a
dedicated trunk into COTC/Teleglobe's "Fujitsu" XB Gateway in Toronto.]
Initially, international gateway operators were able to directly dial
(key-in) a number in a foreign overseas country (rather than having to
'ring-down' the corresponding international gateway operator in that
country), then it was possible for semi-automated operator-keyed IOTC
(direct keying of overseas numbers by originating toll-and-assistance
operators throughout the US and Canada), finally for fully-automated
customer-dialed IDDD to various foreign countries.

Sources/References/Bibliography:

- "Notes on the Network" (1980), as well as:
- "Notes on Distance Dialing" (1961, 1968, 1975),
- "Notes on Nationwide Dialing" (1955),
- "Notes on Nationwide Operator Toll Dialing" (1945/46),
- (Notes on) "The General Toll Switching Plan" (1930);

- Distance Dialing Co-Ordinating Handbook
annual editions from 1971-81, particularly 1976 and 1977 editions;

- "Switching Technology: 1925-75", a volume in the series/set:
"A History of Engineering and Science in the Bell System".
The "Switching" volume authored by Amos E. Joel, Bell Labs, retired;

- "Engineering and Operations in the Bell System" (1983, 2nd edition);

- various articles in the three major 'Bell System' journals/magazines
from the 1940's through 1970's:
- "Bell Telephone (Quarterly) Magazine",
- "Bell Laboratories Record",
- "Bell System Technical Journal".


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