three companies over its 20-year lifetime. Digital Equipment Corporation The software that eventually became CT Connect was originally developed in the late 1980s at Digital Equipment Corporation. During the 1980s, telephony was evolving from analog to digital technology. The international telecommunications standards body CCITT (now the ITU) published specifications for the Integrated Services Digital Network (ISDN). The ISDN specifications define digital interfaces between a subscriber and the network that can simultaneously support multiple telephone calls and packet data transmission. In the 1980s Digital Equipment was a leader in computer networking with its DECnet software. Digital Equipment studied the ISDN specifications and concluded that the ISDN interface lacked the ability to coordinate a voice call with related data. The Digital Equipment team named this capability computer integrated telephony (or CIT) and evangelized the concept among vendors and customers. (The acronym for the original Digital Equipment product line, CIT, is frequently confused with the industry acronym for any form of computer-telephone integration, CTI. The latter term was adopted by members of the MultiMedia Telecommunications Association (MMTA), a prominent US industry association. The MMTA was incorporated into a larger trade association, TIA, in 2000.) (See and for early expositions of the CTI concept by Digital Equipment.) Digital Equipment needed the commercial cooperation of telecommunications equipment manufacturers because their telephone switching systems had to be modified to report telephone call information via new CTI data links. Two Canadian private branch exchange (PBX) manufacturers that were interested in the idea: Northern Telecom (now Nortel) and Mitel, which at that time was controlled by British Telecom. Digital Equipment worked with both of these companies – one in Canada and one in the United Kingdom – to design and implement CTI data links between their respective products. Both efforts were successful, and systems using PBXs from both companies were shown at the quadrennial CCITT exhibition in Geneva in the fall of 1987. Digital Equipment released its first CTI software products, operating with the Mitel SX-20 and Northern Telecom SL-1 PBXs, the following year. Between 1988 and 1992, the Digital Equipment team approached more telecommunications equipment manufacturers (including Siemens ROLM and the former AT&T, whose Definity PBX product line is now owned by Avaya) and implemented the additional protocols needed to interoperate with their telephone systems. However, it quickly became clear that the number of proprietary protocols was becoming unmanageable. Call models differed between telephone systems, making it