Point of presence (PoP) is a carrier facility that offers dial-up or leased-line access to its network for the purpose of providing services to customers. PoPs are configured with equipment and lines appropriate for the types of services that are offered from those locations. Examples of PoPs include:
■ A local telephone company’s central office
■ A long-distance carrier’s toll office
■ An Internet service provider’ (ISP) modem bank
■ A national Internet backbone provider’s metropolitan-area exchange (MAE) or Network Access Point (NAP)
■ A cellular carrier’s, paging company’s, or wireless data service provider’s base station transceivers
PoPs may be shared by several service providers. The NAPs on the major Internet backbones, for example, are equipped to handle large amounts of traffic to avoid bottlenecks on the Internet. The largest NAP, located in Chicago, is operated by Ameritech Advanced Data Services (AADS). The NAP has more than 40 companies, Internet service providers and universities connected to it via DS3 (45 Mbps), OC-3c (155 Mbps), and OC-12 (622 Mbps) Asynchronous Transfer Mode (ATM) connections.
Even company Web sites are called PoPs. When a company locates its Web server at an ISP’s PoP to take advantage of its security and management services, the arrangement is sometimes referred to as a Virtual PoP.
Points of Presence are the locations from which network services are provided. If a carrier does not have a local point of presence from which corporate customers can access the service, the carrier can route the traffic to the nearest PoP at little or no cost to the customer if the traffic volume makes the backhaul arrangement worthwhile. For consumers, the back-haul arrangement might be in the form of toll-free 800-number access to the nearest PoP.