Peer-to-peer: a network that relies mainly on the infrastructure and bandwidth of the network participants for the exchange of traffic (ie voice, video, data).
Private automatic branch exchange
Packet switching
The transmission of data that has been broken down into fixed-sized pieces –  ie “packets” – which contain header information including the network address of the sender and the destination, enabling them to traverse different routes and be reassembled at a remote location. Packet switching takes advantage of the “bursty” nature of data applications and because it facilitates sharing of physical transmission resources, is used to increase the volume of traffic that can be sent at any one time on a given circuit. X.25 is the classic example of a packet-switched network technology.
Collection of open, technology-independent application programming interfaces (APIs) that enable the development of applications that operate across converged networks. Parlay (aka Parlay X) integrates internet multimedia networks and intelligent networks (IN) with IT applications via a secure, measured, and billable interface and is used by network operators to generate new revenue streams from value-added services.
Provider backbone transport
Private branch exchange
Personal communications network
Personal digital subscriber line
Power distribution unit: device used in data centres for distributing electric power by taking high voltage and amperage and reducing it to more common and useful levels – from 220V 30A single phase, to multiple 110V 15A or 110V 20A plugs.
Phantom traffic
Telephone traffic that terminates at a local exchange where the originating carrier has manipulated or stripped information from the CDRs or signaling messages in order to avoid paying access charges.
Physical specifications
Percent of local usage: carriers provide this figure to each other on a regular basis in order to identify the jurisdiction of each call type carried over their trunk groups.
Point of interconnection/point of interface: the physical interface between the Lata access and interlata functions. It is also the demarcation point between the local exchange carrier and a wireless service provider, which establishes the points for testing and the technical interface.
Passive optical network: comprising an optical line termination (OLT) at the carriers’ central office and a number of optical network units (ONUs) near end users, a passive optical network is a system that eliminates expensive network elements and enables carriers to reach a large number of end-points at  comparatively low cost.
Point of presence
Point of termination
Plain old telephony service
Private line
A direct circuit or channel dedicated to a specific end user that bypasses the interexchange carrier.
Protected/ unprotected circuit
A circuit is “protected” if it uses “self-healing” transmission technology – ie if one route fails, traffic is automatically redirected over the diverse standby route.
Pseudowire technology effectively turns the OSI model upside down because it can be used to carry any type of Layer 1 or 2 traffic over a packet architecture. A pseudowire emulates a point-to-point link and provides a single service perceived by its user as an unshared link or circuit.
Perceptual speech quality measure
Public switched telephone network
Postal, telegraph and telephone operator
Public exchange
The European term for central office (see CO)
Permanent virtual (data) circuit
Player versus environment term used in online computer role-playing games to describe any situation in which a player must complete a pre-defined task without fighting other players.
Player vs Player is competitive interaction within a game between two live participants. This is in contrast to games where players compete against computer controlled opponent.
Persistent virtual world