AT&T 4ESS Tandem List

 

The following is a work in progress in trying to maintain an active catalog of the Number 4 Electronic Switching System (#4ESS) Class 4 Tandem list for the AT&T long distance network. This list is a successor to the original list made by the late telephone historian and researcher Mark Cuccia (1961-2014) to try to encompass the changes in the #4ESS network since his passing.

The #4ESS switch was first installed in Chicago, IL in 1976 as the successor to the 4A crossbar switch. Over 100 #4ESS switches were installed in the PSTN by the early 1990s for AT&T Long Lines, and a number of them were also used for the regional Bell operating companies. A second batch of #4ESS switches (what I call “2nd Generation”) were installed in 1998-1999 and were the last #4ESS switches installed in the PSTN, with the one in Atlanta (number 146-T) being the last one ever.

Starting in or around 2012, a new batch of #4ESS type Class 4 switches were starting to show up in the PTSN. This is the successor switch called the Next Generation 4ESS or N4E. The N4E emulates the #4ESS software in a new hardware environment. The main difference to the end user is that the tandem recordings are very clean (no magnetic drums) and sound a bit robotic in nature.

This list not only contains the #4ESSes in the network, but the new N4E switches as well. In some cases, there are N4E switches that are replacing 4ESS switches, and in some cases they are brand new to the network (those numbering 147 and higher). It is assumed that the new N4Es are replacing the #5ESS switches that were originally installed to be “edge tandems” in the AT&T network and upgrading them to full Class 4 tandems.

The locations for the new N4E switches are best guesses, and in some cases appears to be replacing existing #4ESS switches and taking on new identities, while in other cases they take on the old trailer code of the #4ESS that they replaced.

Trailer
Code
(xxx-T)	Location		Type	Install Date	Notes
001	WINDERMERE FL		4ESS	(03/1991)	Verified Jan 2022
002	ALBUQUERQUE 2 NM	4ESS	(11/1977)	
003	ALBANY 3 NY		4ESS	(01/1982)	
004	ANAHEIM 3 CA		4ESS	(03/1981)	Possibly replaced with 158-T?
005	ARLINGTON 3 VA		4ESS	(04/1982)	
006	ATLANTA 5 GA		4ESS	(03/1982)	
007	ATLANTA 4 GA		N4E	Replaced	Verified Jun 2022
008	AUSTIN 2 TX		4ESS	(01/1987)	Verified May 2022
009	BUFFALO 2 NY		4ESS	(06/1984)	
010	BALTIMORE 10 MD		4ESS	(08/1980)	Verified Apr 2022
011	BIRMINGHAM 2 AL		4ESS	(04/1981)	
012	BATON ROUGE 2 LA	4ESS	(03/1984)	
013	NEW YORK 5410 NY	4ESS	(07/1991)	
014	CHICAGO 9 IL		4ESS	(08/1987)	
015	CHARLOTTE 3 NC		4ESS	(05/1980)	Verified Apr 2022
016	CHARLESTON 2 WV		4ESS	(02/1982)	Verified May 2022
017	CLEVELAND 3 OH		4ESS	(12/1979)	Verified Apr 2022
018	COLUMBIA 2 SC		4ESS	(11/1981)	Verified Jun 2022
019	COLUMBUS 3 OH		N4E	Replaced	Verified Jun 2022
020	COLORADO SPRINGS 2 CO	4ESS	(10/1981)	Verified May 2022
021	CAMBRIDGE 19 MA		4ESS	(12/1984)	
022	CAMDEN 3 NJ		4ESS	(04/1979)	Verified Jun 2022
023	CINCINNATI 2 OH		4ESS	(06/1979)	
024	DES MOINES 2 IA		N4E	Replaced	Verified Apr 2022
025	DALLAS 3 TX		4ESS	(12/1976)	Possibly replaced with 154-T?
026	DALLAS 4 TX		4ESS	(04/1981)	Possibly replaced with 154-T?
027	DENVER 5 CO		N4E	Replaced	Verified May 2022
028	DETROIT 3 MI		4ESS	(04/1981)	(Disconnected circa 2003?)
029	DAYTON 2 OH		4ESS	(02/1987)	
030	FREEHOLD 2 NJ		N4E     Replaced	Verified Jan 2022
031	FRAMINGHAM 4 MA		4ESS	(05/1987)	Verified May 2022
032	FORT WORTH 2 TX		N4E	Replaced	Verified Jun 2022
033	GRAND RAPIDS 3 MI	4ESS	(05/1984)	Verified Jun 2022
034	GREENSBORO 3 NC		N4E	Replaced	Verified Jun 2022
035	GARDENA 3 CA		4ESS	(06/1987)	Verified Jun 2022
036	HARRISBURG 2 PA		N/A	Replaced	Changed to a 5ESS
037	HOUSTON 4 TX		N4E	Replaced	Verified May 2022
038	HOUSTON 5 TX		4ESS	(07/1988)	
039	INDIANAPOLIS 2 IN	4ESS	(10/1980)	
040	JACKSON 2 MS		4ESS	(04/1983)	
041	JACKSONVILLE 3 FL	4ESS	(12/1976)	
042	KNOXVILLE 2 TN		4ESS	(12/1980)	Verified May 2022
043	KANSAS CITY 2 MO	N4E	Replaced	Verified Jun 2022
044	LANSING 3 MI		4ESS	(05/1987)	Verified May 2022
045	LOS ANGELES 5 CA	4ESS	(02/1983)	
046	LOS ANGELES 6 CA	4ESS	(04/1988)	
047	LOUISVILLE 2 KY		4ESS	(07/1980)	Verified May 2022
048	LITTLE ROCK 2 AR	N4E	Replaced	Verified May 2022
049	MACON 3 GA		4ESS	(04/1987)	Verified May 2022
050	MIDLAND 2 TX		4ESS	(10/1983)	Verified Jun 2022
051	MEMPHIS 2 TN		4ESS	(02/1981)	Verified Jun 2022
052	MANCHESTER 3 NH		4ESS	(04/1982)	Verified May 2022
053	(presently unassigned)	N/A	N/A	        N/A
054	MINNEAPOLIS 3 MN	4ESS	(05/1980)	Verified Jun 2022
055	MINNEAPOLIS 4 MN	4ESS	(06/1988)	
056	MONTGOMERY 2 AL		N4E	Replaced        Verified Jan 2022
057	NORFOLK 4 VA		4ESS	(04/1981)	
058	NASHVILLE 2 TN		N4E	Replaced	Verified May 2022
059	NEW HAVEN 5 CT		4ESS	(10/1981)	Verified Jun 2022
060	NEW ORLEANS 3 LA	4ESS	(06/1980)	
061	NEWARK 8 NJ		4ESS	(06/1980)	Verified Apr 2022
062	NEW YORK 24 NY		4ESS	(04/1978)	
063	NEW YORK 51 NY		4ESS	(11/1984)	
064	NEW YORK 5450 NY	4ESS	(01/1981)	
065	NEW YORK 12 NY(QUEENS)	N4E	Replaced	Verified May 2022
066	OJUS 3 FL		4ESS	(05/1978)	
067	OAKBROOK 2 IL		4ESS	(03/1981)	
068	OAKBROOK 3 IL		4ESS	(06/1988)	
069	OKLAHOMA CITY 2 OK	4ESS	(05/1979)	
070	OAKLAND 6 CA		4ESS	(08/1981)	
071	OMAHA 2 NE		N4E	Replaced	Verified Jun 2022
072	ORLANDO 3 FL		4ESS	(09/1980)	
073	PEORIA 3 IL		4ESS	(02/1983)	Verified May 2022
074	PHILADELPHIA 4 PA	4ESS	(05/1980)	Verified May 2022
075	PHOENIX 3 AZ		4ESS	(09/1980)	
076	PITTSBURGH 3 PA		N4E	Replaced	Verified Apr 2022
077	PORTLAND 3 OR		4ESS	(04/1979)	
078	RICHMOND 2 VA		4ESS	(05/1979)	
079	ROCKY MOUNT 3 NC	4ESS	(06/1982)	
080	ROCHELLE PARK 3 NJ	4ESS	(08/1982)	
081	RENO 4 NV		4ESS	(05/1982)	Verified Apr 2022
082	SOUTH BEND 3 IN		4ESS	(04/1987)	Verified May 2022
083	SACRAMENTO 4 CA		N4E	Replaced	Verified Jun 2022
084	SHERMAN OAKS 5 CA	N4E	Replaced	Verified Jun 2022
085	STOCKTON 3 CA		4ESS	(03/1984)	Verified Apr 2022
086	SALT LAKE CITY 2 UT	4ESS	(04/1982)	Verified Jun 2022
087	SAN ANTONIO 2 TX	4ESS	(05/1977)	
088	SAN DIEGO 3 CA		N4E	Replaced	Verified Jun 2022
089	SAN FRANCISCO 4 CA	N4E	Replaced	Verified May 2022
090	SAN JOSE 3 CA		4ESS	(03/1982)	Verified May 2022
091	SPRINGFIELD 2 IL	4ESS	(04/1985)	Verified Apr 2022
092	SPRINGFIELD 3 MA	4ESS	(05/1980)	Verified May 2022
093	SPOKANE 2 WA		4ESS	(10/1982)	Verified May 2022
094	SAINT LOUIS 3 MO	N4E	Replaced	Verified May 2022
095	SEATTLE 4 WA		4ESS	(05/1980)	Verified Jun 2022
096	SYRACUSE 2 NY		4ESS	(03/1985)	Verified May 2022
097	TAMPA FL		4ESS	(11/1986)	
098	TOLEDO 2 OH		4ESS	(04/1984)	Verified Jun 2022
099	TULSA 2 OK		4ESS	(06/1980)	
100	WASHINGTON 6 DC		4ESS	(03/1978)	
101	WAYNE 2 PA		4ESS	(09/1977)	Possibly replaced?
102	WICHITA 2 KS		4ESS	(04/1981)	
103	WHITE PLAINS 3 NY	4ESS	(01/1987)	
104	WHITE PLAINS 5 NY	4ESS	(08/1980)	Verified Jun 2022
105	WAUKESHA 3 WI		4ESS	(03/1979)	
106	WEST PALM BEACH 4 FL	4ESS	(08/1981)	
107	AKRON 4 OH		4ESS	(04/1989)	
108	ATLANTA 7 GA		4ESS	(11/1988)	
109	BLOOMINGTON 2 IN	4ESS	(11/1989)	
110	CHICAGO 11 IL		4ESS	(01/1990)	
111	NEW YORK 55 NY		N4ES	Replaced	Verified May 2022
112	PLYMOUTH 2 MI		4ESS	(12/1989)	
113	SAN BERNARDINO 2 CA	4ESS	(03/1989)	Verified Jun 2022
114	TUCSON 3 AZ		4ESS	(10/1989)	Verified May 2022
115	PITTSBURGH 9 PA		4ESS	(12/1988)	
116	OMAHA 3 NE		4ESS	(07/1990)	
117	HAMILTON SQUARE 2 NJ	4ESS	(07/1991)	
118	WORCESTER 3 MA		4ESS	(12/1991)	
119	CHESHIRE CT		4ESS	(01/1992)	Verified Apr 2022
120	NEW YORK 25 NY		4ESS	(02/1992)	
121	HILLSBORO MO		4ESS	(05/1992)	
122	FINKSBURG MD		4ESS	(07/1992)	
123	ADAMS TX		4ESS	(10/1992)	Verified May 2022
124	PLANO IL		4ESS	(12/1992)	(standby tandem)
125	ELLISVILLE FL		4ESS	(10/1992)	
126	MONTICELLO 2 GA		4ESS	(10/1992)	Verified May 2022
127	CEDAR KNOLLS 2 NJ	4ESS	(10/1992)	
128	TACOMA 2 WA		4ESS	(12/1992)	
129	DUNNIGAN CA		N4E	Replaced	Verified Apr 2022
130	GARDENA 4 CA		4ESS	(04/1993)	Possibly replaced with 152-T?
131	FORT LAUDERDALE FL	4ESS	(05/1993)	Verified May 2022
132	MADISON 3 WI		4ESS	(11/1992)	Verified Jun 2022
133	WHITE PLAINS 4 NY	4ESS	(08/1993)	
134	MARKHAM ON    (905-U2)	4ESS	(06/1993)	Possibly retired
135	CHERRYVILLE NJ		4ESS	(05/1993)	
136	CAMBRIDGE MA		4ESS	(06/1993)	
137	ALDERGROVE BC (604-U2)	4ESS	(08/1993)	Possibly retired
138	OXNARD CA		4ESS	(07/1993)	
139	ANCHORAGE AK		4ESS	(03/1996)	Verified Jun 2022
140	MESA AZ		4ESS 2nd Gen	(1998/1999)	
141	DURHAM NC	4ESS 2nd Gen	(1998/1999)	Verified Jan 2022
142	DENVER 6 CO	4ESS 2nd Gen	(1998/1999)	
143	FORT MYERS FL	4ESS 2nd Gen	(1998/1999)	Possibly replaced
144	MONROVIA MD	4ESS 2nd Gen	(1998/1999)	Verified Jun 2022
145	CHICAGO IL	4ESS 2nd Gen	(1998/1999)	
146	ATLANTA GA 	4ESS 2nd Gen	(07/1999)	Last traditional #4ESS
147	CHICAGO IL (?)		N4E	2012?	
148	BOSTON MA (?)		N4E	?	
149	MESA AZ (?)		N4E	?	        Verified May 2022
150	ATLANTA GA (?)		N4E	?	
151	FORT MYERS FL (?)	N4E	?	        Verified May 2022
152	GARDENA CA (?)		N4E	(08/2013)	Verified Apr 2022
153	??? MA (?)		N4E	?	        Verified Jun 2022
154	DALLAS TX (?)		N4E	?	        Verified May 2022
155	SCOTTSDALE AZ (?)	N4E	?	        Verified May 2022
156	SYRACUSE NY (?)		N4E	?	        Verified May 2022
157	JACKSONVILLE FL (?)	N4E	?	        Verified Jun 2022
158	ANAHEIM CA (?)		N4E	?	        Verified May 2022
159	WAYNE PA (?)		N4E	2016?	        Verified Jun 2022