A Point of Presence (PoP) is the physical location where a network connects to the Internet. For example, the physical point where an Internet Service Provider (ISP) is connected to the Internet is a PoP.
The term Point of Presence (PoP) was coined during the breakup of the Bell Telephone system in the 1950s. During that time, a PoP was the point of demarcation between the telecommunications network managed and operated by a long-distance carrier and the network managed and operated by a local telephone network. The same basic premise holds true today when the term PoP is used relative to the Internet. With regard to the Internet, the term PoP is most frequently used to refer to the physical point of demarcation between a telecommunications provider's massive network and a local Internet Service Provider (ISP).
Also See: Interent Service Provider
Frequently Asked Questions
Does an ISP have just one PoP?
A small independent ISP, with a single office location and a handful of employees, may only have a single PoP through which it routes its customers onto the Internet. However, large ISPs may have dozens or even thousands of PoPs in order to provide service across a large geographic area.
Does the ISP always own the PoP?
An ISP may or may not own the PoP at which they connect customers to the Internet. In many locations around the world, there are massive data centers in which corporate customers, ISPs, and large-scale web applications rent space and share access to world-class bandwidth. ISPs may use these types of data centers to locate a PoP since this type of facility often has links to the Internet with more bandwidth than what the ISP could afford to establish on their own.
If an ISP uses a data center to establish a PoP they will rent the physical space that the PoP occupies, and they may or may not own the hardware required to operate the PoP.
Are some ISPs also telecommunications networks?
The line between an ISP and the telecommunications networks that form the backbone of the Internet is very blurry. The largest telecommunications companies in the United States include household names such as Century Link, Charter, Comcast, Verizon, and AT&T. A quick visit to any of these companies websites will show that they offer Internet service for businesses and individual consumers. At they same time, they are so large that their networks combine to form part of the backbone of the Internet. In other words, in the case of the largest ISPs, a PoP may be used to refer to a point within their own network that connects one part of the network to their larger network infrastructure.
How does the term PoP come into play in the case of the Internet delivered over a cell phone signal?
When you purchase cell phone coverage from a cell phone provider, your phone is in direct contact with the cell phone network of a major cell phone service provider. This is even the case if you purchase coverage from a mobile virtual network operator like Tracfone – ultimately your phone receives a signal directly from AT&T, Verizon, T-Mobile, or Sprint. Since there is no intermediary's hardware between your phone and the telecommunications network, your phone is the PoP. As a matter of fact, in formal documents within the cellular world individual customers are often referred to as PoPs.