With AT&T saying that “with each passing day, more and more communications services migrate to broadband and IP-based services, leaving the public switched telephone network (“PSTN”) and plain-old telephone service (“POTS”) as relics of a by-gone era,” I thought it would be a good time to get a snapshot of the North American telephone network as it exists now. In the early 1970s, phone phreaks like Evan Doorbell and Mark Bernay started recording what they saw as the demise of the electromechanical telephone network. The switches then were crossbars and panels and steps and the like, with early computerized switches like the 1ESS just starting to appear. Now, the 1ESS is nearly gone from the network, and the North American network consists mostly of the Western Electric/AT&T/Lucent/Alcatel 5ESS (the 1ESS’s successor), the Nortel DMS-10 and DMS-100, the GTE Automatic Electric GTD-5 EAX, and the Stromberg-Carlson/Siemens DCO. A few other switches in the network, like the Siemens EWSD and the Ericsson AXE 10 have found more popularity in North America as cellular switches (and as wireline switches in other countries).
The oddball switches are the ones that really interest me, and they’ll be the first ones to disappear from the network. I’ve been told that the TRW Vidar ITS-5 and the Mitel GX5000 switches may be gone from the North American network. To see what might be left, I decided to do some digging, and I’ve come up with a list of the telephone switches (minus remotes) still in use in the North American network. There’s undoubtedly some stale data in this database, and so for rare switches, I think the numbers listed are the upper boundary — the lower boundary may be as low as 0. The list also contains the mystery “Digital Switching System”. There seems to be an awfully large number of them for it to be the North Electric DSS-1, which became the ITT 1210 — maybe it just means “unknown digital switch”?
The picture above of the GTD-5 EAX was shamelessly stolen from the site of a GTD-5 consultant, the only place I could find a picture.
Top 10 Switches
| Manufacturer | Switch | Count |
|---|---|---|
| NORTEL | DMS 100 | 2513 |
| LUCENT | 5 ESS | 2236 |
| NORTEL | DMS 10 | 1968 |
| AUTOMATIC ELECTRIC | GTD-5 EAX | 668 |
| SIEMENS | DCO | 522 |
| DIGITAL SWITCHING SYSTEM | 247 | |
| REDCOM | MDX 384 | 155 |
| ERICSSON | AXE 10 | 102 |
| SIEMENS | EWSD | 91 |
| LUCENT | 1A ESS | 66 |
The Whole List
| Manufacturer | Switch | Count |
|---|---|---|
| NORTEL | DMS 100 | 2513 |
| LUCENT | 5 ESS | 2236 |
| NORTEL | DMS 10 | 1968 |
| AUTOMATIC ELECTRIC | GTD-5 EAX | 668 |
| SIEMENS | DCO | 522 |
| DIGITAL SWITCHING SYSTEM | 247 | |
| REDCOM | MDX 384 | 155 |
| ERICSSON | AXE 10 | 102 |
| SIEMENS | EWSD | 91 |
| LUCENT | 1A ESS | 66 |
| MITEL CORP LTD | GX5000 DIGITAL SWITCH | 64 |
| PACKET END OFFICE | 54 | |
| METASWITCH, INC. | METASWITCH VP3510 | 28 |
| NORTEL | SA1 | 24 |
| LUCENT | 5ESS-2000 SWITCH | 22 |
| NORTEL | DMS 200 | 21 |
| SIEMENS | DCO 21 | 18 |
| METASWITCH, INC. | METASWITCH VP3500 | 17 |
| TEKELEC INC | IX7000 (TM) NEXT GENERATION CLASS 5 SWITCH | 16 |
| REDCOM LABORATORIES | MDX 10K (MODULAR DIGITAL EXCHANGE) | 15 |
| VIDAR | ITS 5 | 14 |
| METASWITCH, INC. | METASWITCH VP2510 | 12 |
| NORTEL | CS 1500 | 12 |
| TEKELEC INC | OPEN COMPACT EXCHANGE (OCX) | 12 |
| COMMUNITY DIAL OFFICE | 12 | |
| CIT-ALCATEL INC | E10 – FIVE SWITCHING SYSTEM | 11 |
| NORTEL | DMS 500 | 11 |
| SIEMENS | CENTURY DCO6000 | 10 |
| AUTOMATIC ELECTRIC | STEP BY STEP | 8 |
| LUCENT | 5ESS-2000 SWITCH VCDX | 8 |
| NEC CORPORATION OF AMERICA | NEAX – 61 | 8 |
| 9A ANNOUNCEMENT-WEATHER | 8 | |
| ANNOUNCEMENT SYSTEM | 8 | |
| SIEMENS | EMD55 | 7 |
| LUCENT | 4 ESS | 6 |
| SIEMENS | XY | 6 |
| HARRIS CORPORATION | RURAL ELECTRONIC EXCHANGE | 5 |
| NORTH ELECTRIC | DSS 1 | 5 |
| ALCATEL | 1210 | 4 |
| ALCATEL | CRX | 4 |
| NEC | NEAX – 61E | 4 |
| NORTH ELECTRIC | DSS | 4 |
| SIEMENS | DTM | 4 |
| TEKELEC INC | 7000 CLASS 5 PACKET SWITCH (T7000) | 4 |
| ALCATEL | 12 (HOST) | 3 |
| LUCENT | 5ESS-2000 CDX (COMPACT DIGITAL EXCHANGE) | 3 |
| METASWITCH, INC. | MG3510 | 3 |
| SIEMENS | DCOSE SMALL EXCHANGE | 3 |
| 4A ANNOUNCEMENT TIME | 3 | |
| CALL AGENT | 3 | |
| VIDAR | IMA2 | 3 |
| ALCATEL | A1 – SPC | 2 |
| METASWITCH, INC. | METASWITCH VP3000 | 2 |
| NORTH ELECTRIC | CX 200 | 2 |
| NORTH ELECTRIC | NX2A | 2 |
| REDCOM LABORATORIES | IGX-MT END OFFICE SWITCH | 2 |
| SANTERA SYSTEMS INC. | SANTERAONE (BOX) BROADBAND OFFICE EXCHANGE | 2 |
| SIEMENS | DCO 80 | 2 |
| SIEMENS | DCO 200 | 2 |
| SIEMENS | ESC(1) | 2 |
| AUTOMATIC CALL DISTRIBUTOR | 2 | |
| ALCATEL | RELAYMATIC | 1 |
| AUTOMATIC ELECTRIC | 375A | 1 |
| GLUON NETWORKS INC. | CLX(TM) CONVERGED LOCAL EXCHANGE | 1 |
| ITEC INC | EMS-1 | 1 |
| LUCENT | 1 ESS – 2WIRE | 1 |
| LUCENT | 1 ESS – 4WIRE | 1 |
| LUCENT | 1 ESS – HILO | 1 |
| LUCENT | 2B ESS | 1 |
| LUCENT | NO 5 CROSSBAR-4WIRE | 1 |
| LUCENT | NO 5 CROSSBAR-ETS | 1 |
| LUCENT | PLEXUS 9000 | 1 |
| LUCENT | STEP BY STEP | 1 |
| NORTEL | CS 100 | 1 |
| NORTEL | DMS-10 AP | 1 |
| NORTEL | DMS10 SIGNALLING RELAY POINT | 1 |
| NORTEL | NO 5 CROSSBAR | 1 |
| NORTEL | STEP BY STEP | 1 |
| NORTH ELECTRIC | CX 30 | 1 |
| ROCKWELL INTERNATIONAL | ISS 3000 | 1 |
| SIEMENS | MAINSTREETXPRESS 36170 | 1 |
| TEKELEC INC | 9000 DISTRIBUTED SWITCHING SYSTEM (DDS) | 1 |
| ANALOG SWITCHING SYSTEM | 1 | |
| CONCENTRATOR | 1 | |
| CROSSBAR SWITCHING SYSTEM | 1 | |
| PACKET SWITCH | 1 | |
| SWITCHED DIGITAL DATA SYSTEM | 1 | |
| LXP – 4 | 1 |
