. Each of the major long distance companies in your area rents space for its own electronic switching equipment at the local tele- phone company central office. The programming in the central office switch will route your call over the network of the long distance company you have selected. There are many companies selling long distance calls, repre- senting a variety of long distance companies. You can buy long distance calls directly from the carrier or from one of these compa- nies which may be called a reseller, rebiller, aggregator or a variation on the same concept. These companies are providing bulk buying, representing large numbers of customers, and are therefore able to negotiate lower rates for the organizations in their group. Since a long distance call has become a commodity in that most calls are of equal quality, not counting cellular service which can vary, one must select a long distance company based upon reputation, service and clarity and accuracy of billing. The cost of a long distance call is based upon many variables. These include 278 The Telecom Handbook CHAPTER 13 distance, time of day, duration, total number of calls made (higher volume = lower costs) and special promotions in effect at the time you select a long distance carrier. Long distance companies provide 800 numbers (may also be 888 or another prefix) enabling callers to reach you without pay- ing for the call. You pay for it instead. This is also called a toll-free number. Along with the 800 numbers, you can buy some sophis- tication in the routing of your calls. For example, you can have a single 800 number with callers from each state routed automati- cally to the nearest branch of your company when they dial the number. Your 800 number can also be programmed to send your calls to your New York office until it closes. After 5PM EST, it will reroute the calls to your California office. You can receive reporting of the telephone numbers of the people who are calling your 800 number. This is called ANI (pro- nounced "Annie") or 