1FB – 1 For Business (aka POTS) A basic, flat rate business line. This is your typical copper pair carrying one line normally with a dedicated number that you can put any analog device on. A 1FB will always be considered a POTS line, but a POTS won’t always be designated a 1FB.

24 – a TV series that ran on the Fox Network here in the States from 2002 to 2009 (off for a year and a half after the actor that plays Jack Bauer got into a DWI on the Pacific Coast Highway around 2007.) The telephones were Cisco product placement (in fact the pilot or the second episode feature NEC sets, then went to Cisco right after.) By 2002, Cisco telephones were under the radar, not to many enterprises had them, and Cisco (and Selisus, the company that produced the Call Manager originally was often a running joke.) The show also had a distinctive ring tone whenever Bauer would call the CTU base, that resembled an Avaya set.

When 24 re-appeared in 2014 as a mini series, the telephones used as a product placement were Avaya. (By 2014, Avaya is now the minority of enterprise systems as Cisco has a hyper majority of control of desksets as Avaya is allegedly struggling being the minority.)

The CTU ring tone despite the ignorance of the VOIP community clearly was based off a “ringback” or “callback” tone from an Avaya telephone. The Fox sound effects department ever invented or created it themselves.  Every time I see someone “wanting a CTU ring tone” on their Avaya set, I cringe. See CTU.

236 area code [fiction] The publisher of this site also kinda resides in a fictional world made with ABS plastic. No not phone material, but Lego bricks. The area code has a lot of significance in close circles of the curator.  In 2000, according to the Publisher’s city records stored on an old Macintosh Color Classic, it serves as the area code for the City and County of Miniland. The area code succeed the very generic 456 area code (really creative for that time  -not!) The decision for 236 was that it wasn’t listed in the Verizon/Bell Atlantic phone book for area codes in North America. However, further research pointed out that it did become a real area code in Canada late the following year. There are safeguards as the country access code is 005 and the country code is 5 so in theory people can’t access the Minifig world, but with the magic of ESS switching, minifigs can in theory call to the outside world.

According to Old World Communications (formerly MT&T, who wanted to sellout the old landlines like everyone else) the 236 area code accounts for 65% of capacity despite it being downgraded itself from a metropolitan major area code to a suburban overlay area code. In 2003, the state required 10 digit dialing for all local calling as a bunch of overlays came popping up. The 236 area code is often found on non functioning telephones or even IP sets tied to a private IP PBX of the Publisher’s residence and SIP handles starting with 236. Some people on eBay might had been lucky to get some sets that had the 236 written on designation strips and weren’t cleared out for sale.

302 – One of the original dial based telephones made by Western Electric

311 – a fictional area code used in movies and Western Electric literature. 311 is now a non emergency number as per to the FCC and is also a “constituent services” number to a bunch of metropolitan cities. 311 went live in Baltimore in 1996 as a simple non emergency line. In 1999, the city of Chicago introduced 311 similarly to most call centers, with the ability to track city services (such as potholes if they weren’t addressed quickly) and had two call centers for those types and uniformed police officers for non emergency, but needing police assistance. In 2003, 311 landed to New York City, raising the bar even higher. Mayor Mike Bloomberg, who founded his financial terminal and media services was a big numbers guy, his company’s internal practices were measured by numbers. The City of New York already had a system in place getting rid of lot of the crime under the previous mayor, Rudy Guliani. Bloomberg took this same system and applied it to the city government, and integrated this into 311. Unlike the Chicago system, the New York City’s 311 could log and track data ranging anything, anyplace or anyone based on 311 calls and use the data to improve the general city’s concerns similar to the crime control a decade before. Most 3-1-1 setups are designed with three systems, VOIP, Contact Center and a database system to track and store data on the 311 requests or complaints. Some cities like Boston have all these systems, but were too stubborn to change the 617.435.3400 to a simple 311 number, meanwhile Somerville, the nearby city, embraced the simple number a few years back. 311 calls have been proven to reduce the actual calls to 911 however, the number is used often during desperate situations such as major blizzards and hurricanes as New York City’s 911 system had been overwhelmed.

IMG_0602500 – the iconic rotary telephone made by Western Electric and was on the market for almost 3 decades beginning in the late 1950s.rebuilt2500

1500 – the first Touch Tone version of the 500 series telephones. The only keys were missing was the star and pound keys, as that was still in development.

2500 – the Touch Tone version of the 500 series telephone. This version includes the star and pound (Octotherp) keys.

5ESS – The fifth generation central office switch originally sold and marketed by AT&T’s Western Electric later AT&T Information Services, then Lucent, later Alcatel-Lucent. During its lifetime, it was installed in over several hundred switching offices. The system can take over hundred thousand trunks and lines to customers for telephone company setups. Mobile and wireless providers also use the 5ESS. The system is designed to handle digital telephony and supports futuristic technologies such as ISDN, T1 and other digital data and telephony services. The switch possibly as of 2015 maybe in extended support, as new components are likely unable to be purchased. A lot of hardware similarities are shared with its PBX cousin, now marketed by Avaya (and new components are sold in different form factors.) The 5ESS was also a replacement product for central offices that still was using the age old electromechanical switching up till the early 1990s. If you didn’t have Caller ID by then, you know you still had that ol beast in your local central office!

66 Block – a wiring block that is an array of 4 electrical blades going across and 50 rows. It’s split up in two pairs at two different connections, and depending on the setup, these blocks could hold 24 to 50 lines on a single block, typically on two different circuits. These wires get sent to the phone company, or the PBX stations. It was named 66 due to a model number made by Western Electric. 66 Blocks were also an interface ports for Key Telephone Systems. This was the days before mass production of electronic systems where ports would be soldered onto printed circuit boards. The customer (or craftsman) would punch wiring onto this block and another pair would be hard wired into the system.

110 Block – a wiring block that is similar to punching down Ethernet cabling. It functions the same as a 66 block, two columns, one to terminate the far away line (say coming from a PBX or Centrex service) and another row goes to the stations. Compared to the 66 block where it uses a special blade to cut and terminate, the 110 block punches down no different than say a Cat 5 drop. (most cases 4 and 5 pins would provide tip and ring.) Nortel claimed ownership for the innovation as it’s also known as a BIX block (if you’re from Canada.) Sucky part? Buttsets typically can’t get into a 110 Block.



AT&T – American Telephone & Telegraph, the dominant telephone company in the United States for over a century. The company also owned 90% of the telephone lines in the country and ran many divisions known as the Bell System, from Western Electric for the phones and switches, the various Bell Operating Companies, Bell Labs, their R&D. AT&T was under a decade long investigation of the Justice Department, and AT&T wanted to be in the IT business, and as such, they made a decision to break up the local Bell Companies effective the first day in 1984. The Long Distance business was retained, though the company started to fall apart, and went into an identity crisis. The IT business failed, and another attempt to get into the business was an acquisition of National Cash Register or NCR in 1991, right after IBM got out of the ROLM phone system investment, the synergies failed, resulting in a massive spinoff  of NCR, as well as getting out of making phone systems and carriers for the phone companies, resulting the spinoff of Lucent Technologies (allegedly it was to do treading waters back to the 1984 provisions) and other spinoffs. AT&T got into the cable business buying the cable giant TCI, to only sell it to Comcast a few years later. AT&T would later be bought by their baby bell, that had just turned 21 at the time of the sale. Southwestern Bell Company or SBC bought AT&T right before 2005, and currently uses the at&t name for brand name use, although its mostly SBC and later BellSouth (that SBC/at&t would buy in 2006) running the show. The American Telephone and Telegraph ended its carnation after that sale.

AUDIX –  (A true) acronym for Audio Information Exchange. First released by AT&T circa 1986, the system was supported by Lucent and now Avaya. Loriaine Nelson is the woman’s voice behind the system, at least prior to recent versions of Modular Messaging. (I’ve read on list-serves Avaya in recent years deliberately made her voice sythentic  to add new prompts instead of calling her themselves to get some new voice overs.)

Like Xerox, Audix became a generalized acronym for voice mail in some offices, even when they weren’t running AUDIX.  This may have been partially due to the default greeting, “Your call is being answered by Audix! [subscriber name] is not available… “ In the later release of Avaya Modular Messaging, the Audix TUI (Telephone User Interface) was offered as an alternative to the stock ARIA TUI(from the Octel acquisition) to help ease users through the conversion.  Audix was available in a card format (TN568) for port networks, and IA770 was offered as software on the S8300 media server available for G700, G350, & G250. It was also offered as a standalone server for larger implementations.

See Nelson, Lorriane, Voicemail

Aastra  – A spinoff of Nortel’s consumer and analog telephone business circa 2000. While the American counterpart AT&T sold theirs to Vtech, the Nortel/Aastra spinoff wasn’t as cheap. Aastra sold “Meridian” analog telephones, including a boxless phone system called the Venture and also sold generic sets with Nortel shells. Aastra ventured off into selling generic IP phones using the SIP protocol and sold other IP phones in different designs (and odd two digit model numbers.) Aastra also acquired some PBX manufactures and would later be sold to Mitel in 2014. As of this writing, Mitel has swiftly integrated both offerings under the Mitel branding.

Asterisk – an open source Linux service (or “daemon”) that provides a Linux machine to run telephony like applications. Originally branded by the community as an “Asterisk PBX”, the service can run as strictly as a voice mail server, a PBX server, auto attendant or IVR services. Asterisk is very software dependent and it’s best audience is similar to a KSU system. It was invented by Mark Spencer who left Adtran around 2000 and wanted a phone system (more on the lines of a Magix or Norstar) but didn’t like the multi thousand dollar price tag. As a result of the arrogance of the open source community who tout that they can write anything and give it out for free, he developed a basic “PBX” for standards of the early 1980s (but with a couple new amenities like voicemail and caller ID) under a company called Digium. Asterisk’s reliability and availability is dependent on the type of computer (as it can run on any PC), its operating system configuration, and how many users and the peak usage.

Since Asterisk has been on the market, different flavors have been on the market. Again Asterisk acts as a “snap in” and functions like DOS and most popular “distros” is FreePBX and Elasix, which kinda like the old Windows, they act as a “graphical environment” to accessing the command line application.

a picture of an 8410 telephone from Avaya

A picture of an Avaya 8410 taken at Boston Medical Center in Boston, Massachusetts.

Avaya – the spinoff of the Enterprise Networks division of Lucent Technologies that occurred in late 2000. What’s in the name? Well it was in 2000, during the go go months of the dot-com bubble, and often pseudo-names came to be. Avaya originally traded on the New York Stock Exchange under the symbol AV until a private equity firm bought the company out by mid 2007. It was hard to sell office phones tied into a generic black box regular Ethernet switches and expect to make a killing. Avaya made a big deal in late 2009 to buy the enterprise networks unit of big telecom company up north. The deal closed by the beginning of 2010, and Avaya assumed the phone system division from Nortel. Avaya since became a household name (like Wikipedia entries) and other stuff overnight. The two entities still act as separate units, and users haven’t really united that well. Avaya’s focus while they were trying to merge the two brands and systems together, they really are going into the path of Nortel. Nortel is in my opinion is for the snobbish, not that I am snobbish too. In 2014, Avaya took a bold step of moving their headquarters which had been there since the early days of the Bell System to a progressive, allegedly innovative region 3,000 miles away in the Silicon Valley region of California, where Nortel had an office.

Attendant Console – A modern word for an operator switchboard. Attendant also means operator. Consoles vary from add on units to a complete multi thousand dollar device. Consoles also vary from the size of the unit, if you have a couple hundred extensions, it may just be a glorified sidecar, if you are a large enterprise, you may have a larger sidecar broken up in pages or in today’s modern world of Voice over IP, you have a web page.

Attendant consoles serve the following

  • Direct access to the trunks relevant to the location or the company
  • multiple lines, call appearances or “loopback lines” (same as the former) to process multiple calls
  • A dedicated clock to show the time of day or a timer to time calls
  • The ability to monitor 9-1-1 type calls (Avaya’s solution is crisis-alert)
  • Alarms, The ability to notify the operator some disruption is effecting PBX usage. Some systems have major or minor alarms
  • The ability to transfer calls faster than a traditional desk phone
  • And to monitor other telephones (see BLF)

Avaya Red – Referring to the unit prior to the Nortel acquisition. Teams who are familiar with Definity, Merlins alike would be under this unit. The company’s color was red prior to the acquisition, hence the name.

Avaya Blue – referring to the unit that was once Nortel’s enterprise unit. The color name was derived by their former color in the logo. Avaya was exploited more and more by the Nortel people than Avaya Red ever was. Today’s Avaya seems to be run by sock puppets in the former Nortel crew, IMHO. All new content (such as pictures depicting any pre 2009 Nortel equipment)  going forward will be referred to this starting in the summer of 2015.

BIX – Nortel’s version of the 110 block, that apparently was patented. It dates back to the late 1980s.

BLF – Busy Lamp Field

Bell System – the operating unit of the old AT&T. The Bell System was comprised by several large divisions, Bell Labs (AT&T’s R&D), Western Electric (the equipment making arm), the local Bell Operating Companies like New England Telephone Company and the long distance (then called Long Lines.) This was mostly AT&T’s business until 1982, when the company settled in Federal court being sued for a monopolistic enterprise. Despite what you see or hear, the US Government really did force AT&T to break up the Bell System.  Between the legal drama going on for a few years and AT&T desperately wanted to be in the IS business, the deal (known as the Divestiture) was that AT&T would break up the 7 Bell Operating Companies (or Baby Bells), and keep Bell Labs, the Long Lines and equipment. The final part of this settlement was in effect on January 1st, 1984, nearly 2 years after reaching the initial settlement. This was due to planning and executing a breakup.

There is a bias towards the Bell System by this publisher, given he was born 3 years after the breakup. An outsider looking in always admired the customer service and quality that made the monopoly seem to be defensive, or that it was a good monopoly. People like the founder of MCI or the writers of Saturday Night Live or if you were a fanboy of say ROLM or Northern, you probably had a beef with them. The Bell System was mocked on TV skits, or was considered some as “arrogant.”  AT&T  made solid profits as money always came in at great margins, which is why the monopoly in the financial sense worked. Some have said the free market such as mass production of telephone equipment and the technological innovation of switching equipment would allow competitors to come in and the Bell System would’ve been dead by marketplace near the end of the 80s.

Today’s monopolies in the mobile and broadband has inflated profits, more shareholder driven and has to report and never fail to Wall Street. Companies today cut corners to again make shareholders happy, while customers complain about service and quality issues.

Barbe, Jane – one of the first known telephone voice over talents. She was well known for “intercept” type of calls that were unable to go through, dialed the wrong number or the circuits were too busy. She also served the voice for early voice mail and voice response systems as far back as the 1960s. She was also known well in the Octel Voicemail systems, serving as a voice for their prompts. Because Octel’s voice mail systems were used by the telephone companies; her voice according to Wikipedia was heard by 300 million people a week, compared to 150 million users before the acquisition by Lucent in 1997. She died in 2003 at the age of 74. When Avaya was spun-off they introduced a new voice mail system called Modular Messaging to provide emulation of Octel or AUDIX. On the other hand,  Loraine Nelson serves the voice over for the competing PBX voice mail system called AUDIX. (See Nelson, Loraine)

Blue Box created by a bunch of Silicon Valley nutjobs (including the founders of Apple, Steve Wozniak and Steve Jobs), they were able to develop a box to override the AT&T Long Lines network by placing free long distance calls by punching telephone numbers at 2500 hertz. This high pitched tone would notify the central office that a long distance call was being placed. The trick was found when another prankster used a Cap’n Crunch whistle (remember the days of free toys in your morning meals?) that mimicked the pitch. See Phreakers

Busy Lamp Field – the ability for users or operators to monitor other extensions if they are off hook to indicate if they should call or transfer calls to those extensions. If users enable Do Not Disturb, the lamp will show busy and its the user’s decision to ether transfer to voicemail or call someone else.

Bridged Appearance  – Similar to call appearances, bridged appearances can give multiple phones access to the same extension. This can emulate the “key phone” experience with the “Line 1, Line 2” setups. In most PBX or Centrex environments with digital, IP or ISDN telephones, you cannot physically daisy-chain telephones like you can do up to about 4 with your home phone service. When you make a call on office telephones, you are talking and dialing directly from the switch in that wiring closet or data center, and your desk set acts as the bridge between you and the switch room. It is basically mini computer terminal. Bridged appearances are more common with all major telephone systems. See the Call Appearances post for more information.

Carrier/Cabinet – A cabinet minicomputer or a carrier is a large refrigerator sized mainframe  designed with a backplane supporting various connectivity using various types of cards. Most cabinets use TDM signaling (ISDN grade 64kpbs) to move the the voice or data traffic between the cards, and typically each row of slots are on a single bus (or train track for layman’s terms.) Some cabinets are small some can be large, and can handle tens of thousands of lines. These are also used in almost every central office in the world. While these mainframe form factors have evolved into smaller rack-sized setups as Media Gateways, these can mimic the old fashioned Carrier/Cabinet setups.

Call Appearance – The idea to have multiple lines on a single extension that doesn’t need additional extension or line numbers.  Simply any type of “call”, outside or inside; ring; page; “buzz” (on some systems) would “appear” on dedicated buttons preset to the extension number. Some call appearances vary by system, and some are easier than others. This makes switching to another call or creating another call easier as you can manipulate multiple types of calls on the dedicated buttons. This feature began with AT&T’s System 75 and 85 PBX systems and was part of ISDN Centrex technologies at the same time, and other systems copied it. For more information on appearances, click here. See also: Directory Number, DN, Call Appearance Call Handling Electronic Key Telephone System (Also known as CA, call-appr)

Call Appearance Call Handling – Electronic Key Telephone System – CACH-EKTS Similar to the previous definition; this one was more of a specification for the use of ISDN telephones during the ISDN craze of the 1990s in the States. This enabled users with Tone Commander, AT&T or Lucent 8500 sets or Northern’s 5300 sets to function similar to their PBX cousins where any type of call that would buzz, ring or make a call “appear” on 3 or more buttons, depending on how many calls that come in. Despite the latter initials, this definition of EKTS is than likely “emulating” the abilities of an on site KSU or KTS, since most of these ISDN sets were used in Centrex setups. Since this technology is over a generation old, it appears that CACH and EKTS were interchangeable terminologies in the Centrex world. See Bridged Appearance, Centrex, and Call Appearance

Call Manager Express – A commonly known name currently known as Cisco’s Unified Communication Manager Express. Known as CME as well. Up until version 4, it was known as Cisco’s IOS Telephony Services or ITS. The code was most likely due to an acquisition of a company not related to Selsius, since ITS didn’t exist till version 3. It’s an app that runs on top of IOS that mimics a smaller version of the Unified Communications Manager. It lives in the flash memory. Version numbers skipped to be aligned similar to it’s soft-switch sibling known as the Cisco UCCM.  See CME, UCCM, Call Manager

Centrex – Central Exchange. It was first available from New York Telephone in the late 1960s as an alternative to a PBX. Centrex allowed customers to have a PBX-like service without dedicated hardware on site. It also could infinitely grow – as much as the phone company had available. Centrex isn’t a very fancy technology ether. In some cases if users wanted paging, hands free intercom, the easiest way was to install Key Telephone Systems and interconnect the Centrex lines to the KTS. Some have used Centrex as lines for PBX systems as Centrex Lines were cheaper than PBX trunks for a period of time. as ISDN technology would become available, some Centrex shops were able to take advantage of having modern operator consoles, ISDN sets were also available to end users. Today’s rendition of Centrex can be considered as “cloud” services using Voice Over IP and programming IP sets to connect directly to the Internet, in many cases there is very little hardware beyond the telephones. Read here for more information. Also known as Cenpack, Centron, etc as Centrex was still a trademark of AT&T for many years after Divestiture.

“Cheaper to Keep Her” – an idiom derived from the probate court system where divorces could be more expensive than just staying together. In recent years with the rise of VOIP and IPT, in fact some established locations that invested heavily in TDM telephony, that it would be more cost prohibitive to upgrade, especially if a data network can barely handle existing data traffic. (Of course the hosted SIP providers will cover this up immediately!)

The more lucrative business opportunities isn’t to toss a phones in dumpsters and turn PBX switches to bookcases (Nortel) or keg dispensing (Avaya); but to enable VOIP as analog or digital lines (obviously through conversion) and any other “shiny object” that VOIP marketers sell, can be done via apps or web based platforms, while they can work together with the generations old hardware.

CME – See Call Manager Express

CTU  – Counter Terrorism Unit, a fictional agency known from the TV series 24. The ring tone (known by the said initials) is very popular in the VOIP community since the ring tone was synonymous with the Cisco IP Phones featured since the very second or third episode in the series. It is most likely this is an aftermarket ring tone.  What is even more amusing is how people “want their CTU ring tone” on their Avaya sets- when in fact the ring tone is derived as a “callback” from one of the original 8 ring tones of the system. You can’t fix stupid!

Comdial – From the research I’ve gathered, this company was an offshoot of Stromberg Carlson (makers of basic PBX and telephones) in the mid 1980s. By the end of the decade they started to make their own phone systems for the interconnect market. Comdial is well known for the “Impact” and “DX-80” series phone systems. Comdials were made in the States before they went off shore. The sets made from the 90s onward had resemblance of the Norstar and I wouldn’t say a “cheap knockoff” like other sites will describe to you. Comdial was bought out by Vertical Communications, a startup circa 2004 and their legacy still lives on under the Vertical name.

ComKey – a switchless Key Telephone System made by AT&T’s Western Electric unit and sold through the Bell Operating Companies prior to 1984. The successor system was the Merlin series. The ComKey required a “master” phone and any other set to be used as “slaves” The master phone received all incoming and outside calls from the phone company and be distributed through the slaves from that telephone. The phones thetelephonebook_Page_101_Image_0001 2maxed with up to 4 lines and 16 stations and despite it’s switchless system add on components such as music on hold and paging could be done through addons located in the wiring closet. Despite being the first electronic telephone, configuring the ComKeys, based on research required intense wiring in the master set and to the slaves. Even with its electronic nature, the set supported both touch tone and rotary dialing!

Conference Calling – is a type of special telephone system (separate from a PBX or Centrex service) that allows multiple parties to have large meetings over the phone. Users call a special number, log in a PIN code, and the operator will facilitate calls using a special console. If a person wants to speak, s/he hits a special feature access code to alert the operator to ether queue them up or to give them the mic so to speak. Sometimes concalls are mistaken with three to six way calling, speaking to a single party over a Polycom, or any other generic set with a loud speaker. For more on Concalls, click here.

Consent Decree (1982) – On January 6th, 1982, AT&T settled with the US Justice Department for a monopoly of telephone services and equipment. At that time, AT&T had 90% coverage of the country. In those days AT&T was a holding company of nearly 30 something businesses including local Bell operating companies, Western Electric and the long distance services (known as “Long Lines”) Their freight truck of telephone services was the center focus of the investigation as MCI, claimed AT&T would not allow them to “interconnect to the Bell telephone system.” The Decree did not state how AT&T would be broken up, logistically.

For nearly a year and a half with heated debates with corporate and local management and clarifications with Judge Harold Greene (who presided the trial) by mid 1983, AT&T had the plan to break up the company into 7 “Baby Bells” and retain manufacturing and enter into the computer business (as they were banned in a 1958 Consent Decree against Ma Bell.)

AT&T basically broke apart. They didn’t know how to sell because they were a utility. They knew nothing about bits or bytes outside of any telephony application. Some even compared January 6th to a level of some tragedy to the country. AT&T’s Long Lines would fall short with competition. As previously described, AT&T in 21 years would be gobbled up by the Baby Bell, SBC Communications and not be the same. The AT&T building that once headquartered the Bell System is now just office space for Thompson/Reuters (as of 2012)

The debate of was America better off with a breakup or not is still debatable for today’s standards. Would the iPhone or say the Web or Facebook or even Twitter be allowed under the old AT&T? It’s very important to note that the breakup in 1984 occurred during the early years of personal computers, and TCP/IP just hit the nerdy lexicon at the time of the trial. There is a possibility that there was a sub-culture of people really rebellious of AT&T that prayed upon the Internet and Personal Computers; but in the dark realities of 1982, when you see the grainy video (even for 1982 standards) of Charles Brown’s announcement of the breakup; the reality was people were still “leasing” phones and so many people, did in fact still have rotary dials and PBX systems were not widespread.

Love them or hate them, the 1982 Consent Decree was the end of a piece of Americana history.

Crossbar Switch – similar to the Step by Step, just this one interconnects telephone lines in a different way. Step by Steps are wired through various motors in cylinder fashion, in crossbars, calls are made and placed through motorized bars.


Definity – A branding for PBX systems produced originally by AT&T’s Information Systems unit, later

an image from Business Data Communications textbook featuring several carrier switches and phones from the then AT&T Definity lineLucent Technologies then Avaya Inc. Its a contraction of Definitive Solutions for Infinite Amount of Possibilities, according to marketing materials of Lucent. The name came to merge 2 large PBX, the System 75 and the System 85 switches.  The said system’s rebranding occurred in announcement on February 6th, 1989. Early TV ads (such as the “flying train”) stated “Definity 75/85”.

The branding has been since renamed to Communication Manager and now Avaya Aura (what a diversion of a name!) Its legacy systems dates as far back as 1984 starting with the System 75, and the System 85 about the same age plus 10 due to legacy code from the Dimension system. The Definity has been rebranded as “MultiVantage”, “ECLIPS” (a weird acronym), then the plain vanilla Communication Manager, then the most weirdest of all names “Avaya Aura.” Regardless of the name changes, the version numbers of the system have remained the same from the System 75/Generic 3 RISC and when you poll up an Aura 6.1, its really Definity Generic 3 R v16.

The Definity class system is one of the most user friendly PBX solution out there, both for an end user, and one for an administrator and for resellers. This system is so sadly under appreciated that this blog is dedicated to this former eco system (second to the Merlin) which is how this guy got into the (already dead) telecom world. As time goes on, more outdated resources of this system will be posted here. See  Avaya, Avaya Red, Oryx/Pecos, DCP, Digital Communications Protocol

Digital Centrex – A term by Nortel (now Genband) for use of delivering Centrex services over digital or analog telephone lines on DMS class switching systems.

Digital Signaling Processor – See DSP

Digital Telephony – the concept of low level electricity using electronic pulses that uses to provide data transfer. Digital telephony was designed in the age of computers and integrated circuits. Digital telephony was developed as far back as the 1960s, first PBX installs were in the mid 1970s by Northern; and carrier rollouts by Northern via the DMS series in the early 1980s. While Western Electric introduced the 5th generation ESS switching unit, to be very honest, most digital telephony did not really come to fruition till the mid 1990s. In the age of the Internet and voice over IP, Europe was a holdout till recently.

Digital Telephony used specific computing that was designed specifically for the use of voice and data. Connections were mostly of T1, BRI and PRI connections of the ISDN flavor. In the PBX front, many of the cutovers of the time replaced the old fashioned cord-board switches or even 800-series electromechinical PBXes (actually no different than the central offices) into computers. Office telephones were basically “terminals” because the computer-based systems were in fact the true “operator”. Why? because all the calls were really placed and received in these mainframe rooms, your operator “switchboard” or desktop telephone were basically “extensions” or devices to the big iron switches. All the touch tones, and hitting a line button was simply sending a command for the phone to receive things like a dialtone, or a call. POTS phones are a totally different animal.

IP Telephony has succeeded Digital Telephony, while retaining some aspects of this idea.

Dimension –  The first and only digital telephone system that was marketed by the Bell System prior to the 1984 breakup of AT&T. Sold by Western Electric, many of these systems were leased in the same fashion as say the consumer sets (as of 2016 writing.) The Dimension was sold in various models, the 400, the 2000 and perhaps 3000. Documentations have been hard to find online because it was property of the Phone Company, and it was protected under the documentation practices. The system was announced in 1974 and lasted for a decade. Unlike the SL-1 (released a year later) Dimensions were ripped off the face of the earth by the 1990s. Some elements of the Dimension was used for the System 85 PBX as a band-aid solution until AT&T developers were able to make a larger version of the System 75 for a scale of up to 30,000 extensions with a crystal clear connections. That wasn’t available for the market until the mid 90s when the Definity Generic 3 (G3) went to market.

DCP – Digital Communications Protocol, a proprietary protocol for Avaya’s “Definity” like of phones and their systems. Sometimes the term will be used on email lists or pricing sheets from the Business Partners or Avaya themselves. Most IP phones sold by Avaya that uses the H323 IP protocol allegedly routes this same protocol through the open IP network using Port 1709 (if I am not mistaken.) With other proprietary protocols being reversed engineered to use on no proprietary systems like Cisco’s Skinny or the Nortel’s UNISTIM, lack of  hobbyist interest is likely the reason why Avaya’s IP phones without SIP can be used on non Avaya systems. (Devs please take note!) See Avaya, Avaya Red, Oryx/Pecos, Definity

DSP – Digital Signaling Processor. This phrase has been common in modern phone systems using VOIP; but the concept goes back a generation. This possibly is used at carriers, but I’m unable to confirm.

A DSP act as the “brain” for any telephones and lines connected on the same system. While the operating system and software resides on one card traditionally, a DSP (known as “tone clocks”, “clock control”, etc.) would be required if one wanted to ether a) call their colleague’s extension, b) dial out on a landline whether if it was analog or a T1 or ISDN or c) someone trying to call on another extension in a different format such as VOIP, POTS or a digital or even ISDN.

DSPs or it’s equivalent is finite, and can handle up to whatever amount of concurrent calls it can support and what the customer’s setup. They come in different types. Typically in modern telephony environments, DSPs typically “handover” calls once the ringing stops and typically don’t need much management once someone answers, the cards on say an analog landline and a digital board can talk to each other without intervention of the DSP.

DSPs are essential in VOIP especially if customers want to place outbound calls on legacy trunks. If few DSP boards are installed and too many calls are trying to get placed, the system most likely will be overwhelmed.

“Evergreen Commitment” – a marketing ploy by Northern Telecom in the late 80s/early 90s promising that low level equipment (like phones or line boards) wouldn’t get outdated in software or hardware upgrades. By the 1990s and the rise of the business model of IT that devalued technology as  disposable devices; telecom equipment manufactures backed away and tried to make their equipment outdated. This has been since resurrected under a startup company called UCx that has reversed engineered digital (hardwired) Nortel phones and run them on a modified Asterisk system with special hardware to support the non IP sets.

ESS – Electronic Switching System – the huge switching to provide landline telephone service to customers. Was originally made by Western Electric, later Lucent and now owned by Alcatel essentially discontinued today.

EMetroTel – a company founded by former Nortel engineers whom have reversed engineered proprietary protocols of the Nortel sets to work on a modified Asterisk like system. Both digital and IP Sets from Nortel are supported, except for the first generation TDM sets from the 1970s.  Their mission is to support telephones from the smallest system and also support phones from the largest system. References of “Evergreen” commitment have been said such as this Nortel fanboy, Joe the UCX Guy. Evergreen was similar to AT&Ts promise which both companies broke such backwards compatibility commitments. See Nortel, Norstar, Northern Telecom, Meridian 1, Avaya Blue

“Flying Train” – A commercial ran in the late 1980s by AT&T selling their latest PBX offerings known (at that specific time) “Definity 75/85”. The tag line was “expand, expand and expand” as the train went up in the air. I found this on social media as growing up in the early 1990s the only telephone ads were long distance.


“G” set – the handset form factor used in the 500 model telephones, round and curvy style.

Genband – a company that sells central office equipment and wireless solutions for carriers. They were the ones that bought Nortel’s carrier business during the bankruptcy in 2009.

H323 – an open standard enabling proprietary telephony protocols to carry over IP. Does it sound strange? Well it might; but half of the internet “ports” are proprietary anyways. What this means is network administrators can enter a four digit number on their switches to enable the port and move the traffic so there is no jitter. H323 is basically any proprietary digital telephony standard over the IP network. Typically on the PBX end is a similar DSP or tone clock board to mimic the PBX-terminal relationship. H323 is not typically a cloud standard, and it’s dependent to be connected to a LAN where it can be within it’s 3,000 feet range.

H323’s advantage over SIP? It’s registration is typically a few entries in the IP phone’s setting and a registration such as a user login. Once it looses connection it will act as if it’s dead;  SIP will give you a “dial tone” because it’s not “real” to begin with in it’s protocol. A “dial tone” to make the user feel comfortable could be a life or death outcome of in reality the SIP phone is unable to connect properly

Home Run – Basically wiring starts as a jack (or drop) and ends as a plug. This is how many small systems from Avaya’s Merlin or Partner systems are recommended to be wired as. Also used for IT, even though they suggest to use drop to patch panel.

ISDN – Integrated Services Digital Network

IPT – IP Telephony

IOT  – Internet of Things. This is the consumer equivalent to oIP or IP-hyphen-insert technology here that has existed in the enterprise for over a decade. Obviously, given the simpler name and openness of the technology enables more of a security risk, especially when consumers won’t grasp IP well. In the enterprise, “IP-based” technologies outside of PCs and phones were existent, IP-based HVAC systems, IP security cameras, IP based monitoring. IOT in short – has democratized the “IP based” appliances the enterprise had for years. See oIP

ITS –  See Call Manager Express

Insulators – If you go to Etsy and land on page seeing glass cup like things called “insulators” this was the precursor to the telephone poles. Lines went up on tree branches and these glass barriers protected the person from electrocution or something similar. This also held the wire in place.

Interconnect – back in the height of the Bell System, interconnects were any entity not part of AT&T or the System. This included independent telephone providers and long distance services like MCI. How it worked was they would hook up their service to the “system.” In the equipment sense; providers who sold non AT&T PBX and KSU or even KTS were considered as “interconnects” because if someone wanted to install a SL-1 PBX, the provider then “interconnected” that SL-1 to “the system.” “Interconnect” may be seen online as a representative because the word is still is the lexicon of at least a couple of generations working in the business.

Integrated Services Digital Network – ISDN. It was an official standard by 1987 and basically flopped by the mid 1990s with the advent of TCP/IP. The only niche today is if you are the late Don LaFontaine wannabee and do voiceovers like “In a world..” for movie trailers.  ISDN provides near life like voice quality and the intention was to integrate computers with telephony. This kinda of synergy failed until the advent of Voice over IP. ISDN also tried to break the barriers of the business world to consumers, Small Office Home Office (SOHO) or a micro enterprise such as using an ISDN telephone and allowing the user to have near PBX-like experience rather than using a POTS phone. ISDN was also part of the Signaling System 7 (SS7) that brought things like calling line ID or CLID or “Caller ID” to the masses. It also paved the way to technologies like DSL and other future applications. ISDN in some ways is like the tip and ring for the digital telephony world which allows PBX or KTS users to link their systems or voice mail systems together or future-proofing their investments as a migration to Voice over IP by linking packet systems to the digital systems.

IP Telephony – This is how I explain IPT over VOIP. VOIP is basically voice over technology over the Internet Protocol. VOIP can be used for intercoms, used for commercial two way radio, or virtually anything that resembles some form of basic telephony an IP network. IPT on the other hand basically makes a computer more like an office telephone than say some 2500 set. It basically adds more applications over the very basic VOIP. If you don’t have IPT, all you get is basically the ability in theory to make a phone ring or talk over a network. IPT can give you those goodies like paging, call appearances, voice mail transfer etc. The new fashionable name is called Unified Communications or the technology revolving around SIP.


Jobs, Steve – Founder of Apple Computer, NeXT, revived Pixar and an alleged fan of the Avaya systems, likely attracted by the Merlin systems, as per to a search referral to this publication a couple years ago. Google doesn’t lie!

“K” handset – refers to the handset type that is shaped like a “K”, without curves. Found on 2500 sets made from the early 1980s to present if it’s a repro of a contemporary, “classic” looking .

KSU – Key Service Unit, aka the “brain” of  a key phone system

KTS – Key Telephone System

Key Telephone System – a system where each line is tied directly to the telephone or each line is assigned to the telephones. “Line 1” if you hear in films is exactly the same thing. The direct line to the telco whether its in or outbound is ether tied (if its a 1A2 phone) or assigned (like a Partner telephone.) In PBX systems, this kind of practice can be done in a shared line appearance where a bunch of telephones can be tied to one or several numbers and can “appear” on other sets with the lamp indication if the line is used or not.

Key Service Unit – in the early days of electromechanical key systems, a section of a KTS provided additional features, such as lamps, music on hold, and buzzing. These were “feature cartridges” of the 1960s and 70s. The only difference was at least you paid $500 for something you could see or hold unlike a stupid crypto license and no perpetual fee unless the part died!

Landline – also known as wireline and or plain telephony service or POTS. This technology dates back from the beginning as copper wiring but because of the expense, many are not wiring places anymore with copper forcing customers out of their will to go to fiber, but fiber is so sporadic, the service eligibility varies by exact street locations. Mother nature enabled AT&T to not rewire customers in Texas when Hurricane Ike came roaring in and they also didn’t rewire Connecticut when Hurricane Sandy came sweeping the East Coast. Verizon has done similar practices with Sandy and other storms that have totaled the region.