The Asterisk PBX is not exactly a phone exchange per se, but a software implementation of a PBX that runs on a PC, using the computer's network interface to handle voice over IP, and PCI cards sold by Digium to connect to the phone network.
(CX evolved from the "Automanual" system designed by Edward Clements "Clement eXchange" or "Community eXchange")
CX30 (30 line)
CX60 (60 line)
CX100 (100 line)
CX200 ("broadspan" up to 200 lines)
CX1000 (large CX expandable to 10,000 lines)
MCX A version of the CX product line designed by F.R. McBerty after leaving Western Electric/Bell Labs and becoming President of North Electric.
The McBerty design used an early "wire spring" relay and welded piano wire interconnections rather than complex wire multiples. The system never achieved the reputation of the CX product due to problems with poor contact pressure in the interconnection relays. Despite its much lower cost of production and installation, the level of maintenance required to keep these systems on good order doomed this variation of the CX design.
DSS1 (North's first digital switch for local exchanges)
This later was renamed the ITT 1210 product upon purchase of North electric by ITT.
DSS2
ETS4 (Large #4A-ETS class toll switch based on Ericsson "code switch")
NTS4E (4-wire toll switch with Xbar switches and "Omni" processors)
NX1 (Family NX1A, B, C & D; All based on Ericsson By-Path Crossbar license)
L.M. Ericsson purchased North Electric in the early 1950s and brought this Swedish design to North where it was reworked to conform to U.S. telecommunications requirements.
NX1D (Final production version)
NX1E (NX-1D with OMNI Processor for line/directory, trunk and number-group translation services)
The NX-1E was not a SPC switch, rather it was a conventional path controlled switching matrix with electronic processors (computers) replacing the control, route selection and translation (directory number to line ID) functions.
NX2 (Family Small 90–1800 line CDO Xbar)
NX2 (Original design 1959-60)
NX2A (Improved cabinets ~1962)
UN2 Electrically and mechanically the same as the NX-2A but with design modifications specified by United Telecom (United Telecom/Sprint/Embarq) when they acquired North from L.M. Ericsson in the early 1960s. The "United" version of NX-2A replaced the intercabling connection blocks with wire wrap connections so that switches could be installed or expanded without having custom cable harnesses provided by North Electric.
Switcher Family (NX-2A pre-installed in a trailer for rapid installation or portable/emergency use)
TSW Basic Unit with growth to ~360 lines
TSW2 Expanded unit with growth to ~1200 lines
TSW3 Jumbo unit with growth to system recommended maximums
TSD (toll switch)[30]
AN/TTC-20 568 Line Military Fixed Switch (Used by US Air Force - only one was known in existence at Sembach AB, Germany) (retired)
AN/TTC-30 568 Line Military Tactical Mobile Switch (Used by US Army and Air Force) (retired)
CS2000 (180,000 lines 200,000 trunks TDM and VoIP)
CS2100 (230,000 ports, 125,000 IP phones, 150,000 analog telephones, 125,000 digital telephones, 200,000 IP trunks, 50,025 digital trunks, 32,000 analog trunks, 200,000 SS7 trunks, 4,093 H.323 gateways, 112,000 nodes per host, 99,999 ACD agents)
DMS-10 Carrier Class Switching System (320 ISDN PRI links or more than 20,000 lines) (First "production" class 5 digital switch installed in the North American public telephone network[citation needed])
DMS-10 RLCM (640 line remote)
DMS-10 RSLE (520 line remote)
DMS-10 RSLM (640 line remote)
DMS-10S (super small DMS-10 for very small exchanges, less than 640 lines)
DMS-10M (prepackaged DMS-10, a Community Dial Office in a pre-packaged container/"box")
DMS-100 (large local digital Class 5) (also known as an SL-100 when used as CPE (Customer Provided Equipment or PBX service)
A NortelDMS-100e used by an operator to offer local and long distance services in France
DMS-100/200 (local/toll digital more than 135,000 lines)
DMS-200 (toll digital)
DMS-250 (Equal Access Carrier Switch-digital)
DMS-300 (International Gateway Switch-digital)
DMS-300/250 (combination Carrier/International Gateway 70,000 to 100,000 trunks)
DMS-500 (Local/Toll + CLEC Switch)
DMS-Global Services Platform
DMS-MTX (Cellular MTSO)
Stored Program (SP) (Electronic Stored Program Control using mini-bar switches)
SP1 2-Wire (Local)
The SP1 processor was constructed using Small Scale Integration (SSI) Diode Transistor (DTL) Logic. Two types of memory was used. Processor read/write scratch memory (called CALL STORE) was implemented using a magnetic core variant called Ferrite Sheet. Program and Data Store (used to store Software and infrequently changed data) was implemented using a technology called piggy back twistor - in modern parlance a write once, read many times non-volatile memory system). As was the case with the #1ESS systems, processors and memory were duplicated with automatic comparison of processing results and automatic recovery in the event that a mismatch was discovered. It did not however support the complex recovery mechanism provided in the #1ESS where a processor from one half of the complex could be connected to a mix of memory (both call store and program store) modules from both halves of the complex in order to achieve a working combination. Processor diagnostics would generally narrow a problem down to a board or three.
A SP1 2-wire variant was also available that provided Centrex services.
A version of the SP-1 ESS that could provide both 2 & 4 wire services was also built. The first instance was installed in Vegreville Alberta in 1976 or 1977.
SP1 4-Wire (Toll)
The first example of this switch was installed for Bell Canada, in Thunder Bay, Ontario in late 1973. It provided toll services for North Western Ontario and CAMA (Centralized Message Accounting) for the City of Thunder Bay. The City of Thunder Bay which operated its own Telephone Company installed a number of 2W SP1s.
SP1E (used NT40 processor which was later the first processor system for the DMS-100 Family of switches)
NE-1ESS (Northern Electric version of Western Electric) #1ESS {licensee}[citation needed])
Bell Canada operated NE-1ESS 2 wire switches (some of which also provided Centrex services) in Toronto, Ottawa and Montreal. A 4W NE-1ESS was installed in Thunder Bay to provide telephone switching services (SAGE and AUTOVON)for USA and Canadian bases in that part of North America. The #1ESS was implemented using discrete diode transistor logic. A typical circuit board would implement a single 4 input "NAND" gate. Of the myriad of cards in the system - many were dedicated diagnostic gates. The diagnostic software had a very high (95% +) success rate identifying a single failing card. The success rate dropped quickly thereafter. Drifting Voltage Regulator cards caused a lot of angst.
NE-4A (Northern Electric version of Western Electric) 4A toll {licensee}[citation needed])
NE-5XB (Northern Electric version of Western Electric) #5Xbar {licensee}[citation needed])
