e system itself. Still another approach to wireless communications within the office is to enable workers to use their cellular telephones as a "wireless telephones working with the office telephone system" when they are in the office. This requires an interface with the office PBX and the cellular system that often takes place within a communications server in the office. OVERHEAD PAGING While fewer conventional offices are using overhead paging as a means of locating people within the office, there are still certain environments, such as warehouses and manufacturing fa- cilities, where overhead paging is appropriate and useful. A well-designed overhead paging system requires the knowl- edge of an acoustical engineer to properly space and regulate the speakers. While Telephone Installation and Maintenance companies can and often do install and maintain an overhead paging system, en- gaging an engineer to design the system is a worthwhile investment to enable the system to work properly and preserve your hearing! The paging system typically consists of an amplifier located in the telecommunications equipment room, and cabling connect- ing the amplifier to ceiling speakers. The office telephone system can be programmed to enable some or all users to access the paging system, typically by dial- ing an access code such as "8". Sometimes paging capability is limited to the switchboard attendant only. Some smaller business telephone systems have paging capa- bility built in. The page comes out of the same speaker on the telephone as the intercom. The drawback to this type of paging is that it is usually limited to about 15 telephones and may be 292 is The Telecom Handbook CHAPTER 13 distracting since it is heard on every desktop. (It can be elimi- nated from certain telephones if necessary.) Software And Service Companies Software Developers There are many companies developing a wide variety of soft- ware applications to be used in conjunction with the telephone system. Many of these come and go without ever taking ho