implement the CSTA call model and support the relevant CSTA protocol standards. Several telecommunications equipment vendors have used CT Connect as a laboratory CSTA reference to test their own products' compliance with the standard. Environment Independence CTI servers like CT Connect must operate in a heterogeneous computing environment and must interoperate with other system components chosen by application developers and users. CT Connect takes an "open" stance towards other system components, interoperating with a wider range of components than other CTI servers. This open stance is undoubtedly one reason that CT Connect has survived for 20 years while other competitors such as IBM CallPath and Novell Telephony Services have been discontinued. For CTI servers, important dimensions of interoperation are: Telephone System Independence Many telephone switch manufacturers have implemented CTI links for their products. Some of these are proprietary protocols and some are implementations of the ECMA CSTA standard. Some of these manufacturers also offer their own CTI servers (such as Nortel's Contact Center Manager Server), but those servers generally operate only with that single manufacturer's telephone system. By contrast, the companies that have owned and marketed CT Connect over the years (see the CT Connect history below) have made arrangements with most major PBX manufacturers to get access to their protocol specifications and implement their CTI link protocols. API Independence Computer-telephone APIs have proliferated. Microsoft introduced TAPI, Novell introduced TSAPI, Sun Microsystems introduced JTAPI, and a group of vendors formed the Versit Consortium to better integrate the existing protocol standards and APIs. Some manufacturers have attempted to use CTI API specifications to restrict users to their other products. For example, the Microsoft TAPI specification can be implemented only on the Microsoft Windows family of operating systems, and the Novel Telephony Services CTI server (now discontinued) could be used only on Novell networks. By contrast, CT Connect's client-server architecture permits client modules that offer various CTI APIs, and all client modules can interoperate with a common CTI server module. Operating System Independence Like CTI APIs (see above), most CTI servers operate under only one operating system. By contrast, CT Connect has historically included client and server modules that operate under a range of popular operating systems including the Unix and Microsoft Windows families. History CT Connect has had a significant role in the conception and evolution of the CTI concept and its implementation. The product has been owned and marketed by