Pertaining to the technical aspects of telephones, computer wiring (intra- and inter-building), intercommunication, radio, paging, and other communications systems and networks (excluding computer networks). Traditionally thought of as dealing with voice communications, an increasing amount of computer data (including faxes and multimedia) now flows over telephone lines, blurring any possible distinctions between voice and data. This trend will continue, particularly with the increasing use of ISDN (digital) telephone lines.