cally designed to handle large call centers, such as airline reservation operations, groups of order takers handling catalog sales or help desk/customer service centers. These systems are specialized switches designed to handle high volumes of calls. They route the calls to different groups of agents or representa- tives and provide management statistics. These statistics include how many calls are handled by each person, how long callers wait to be answered, and how many callers are on hold at any given time. Most PBXs can be set up to work as an ACD. The Telecom Handbook 58 287 UNDERSTANDING THE INDUSTRY Many applications linking computer and telephones are being set up in conjunction with an automatic call distribu- tion system. PERIPHERAL SYSTEM INSTALLATION AND MAINTENANCE COMPANIES While many telephone installation companies also sell voice mail, automated attendant, call accounting and facilities man- agement systems, another small group of companies sells only these systems without actually selling the telephone system it- self. The advantage of buying from these companies is that they tend to have more in-depth knowledge of the types of systems they sell than the telephone installation and maintenance compa- nies do. Also, the systems that they sell are often more technologically advanced than the systems sold by the telephone installation and maintenance companies. The disadvantage of working with such a company is that you now have an additional supplier to manage. If you are buy- ing from one of these companies selling peripheral equipment only, be sure that the systems are already working with the type of telephone system with which you plan to use them. Also, be sure that this company has worked with the telephone system installation and maintenance company you are using or is will- ing to do so, SO that you're not left to do a lot of coordination between them during and after the system installation. PERIPHERAL SYSTEM MANUFACTURERS While some business telephone system manufacturers also make periph