ssure high availability. In addition, the PBX was never able to keep up with the fast pace of modem evolution. Thus, the approach of connecting PCs tele- phones to achieve convergence quietly disappeared as organizations began to set up office computer networks or LANs (Local Area Networks). To carry through with Jainschigg's view of the elements needed for convergence, even though the tech- nology was available, the approach failed due to the limitations of logistics and human behavior. It is interesting to observe that some of the newer telephone systems such as that manufactured by 3Com have revived the 'computer plugging into the telephone' concept, but there are new and different technologies underlying this physical similar- ity to the earlier systems. Product Categories Enabling Convergence Some of the building blocks and services that converge voice and data technologies and enable the creation of the modular net- work include: Voice Technologies Faxing Technologies Speech Technologies Telephone Interfaces IP Network Interfaces PBX Integration Products Carrier-class board systems-level products 142 & The Telecom Handbook CHAPTER z Engineering-Based Convergence Concepts Turning the Human Voice Into Transmission Signals That Look Just Like Data Today's "convergence" actually refers to several different concepts, primarily (1) those having to do with engineering and (2) those having to do with applications. The foundation of engineering-based convergence is the process of turning the human voice into digital data signals and transporting tele- phone conversations over the same networks, using the same devices as data transmissions. The protocol (message format) called IP (Internet Protocol) used for sending information around the Internet can also be used to transmit voice. This is called Voice over IP or VoIP. This is already being used by telecommunications service providers in their networks and by some organizations with multiple locations who are using the same circuits and devices to transmit voice and