Glossary

Glossary - P

P-MAC

Packet media access controller.

PABX

PABX is a private automatic branch exchange (PABX). It exists as an automatic telephone switching system that operates within a private enterprise. Previously, such systems - known as private branch exchanges (PBX) - had the requirement of using a live operator. However, since then almost all private branch exchanges existing today are automatic. Now, th abbreviation "PBX" usually implies a "PABX." However, some of the manufacturers of PABX (PBX) systems aim to distinguish their products from other companies by creating all new kinds of private branch exchanges. For example, Rolm offers a Computerized Branch Exchange (CABX) whilst Usha Informatics offers customers a Electronic Private Automatic Branch Exchange (EPABX).

Packet Switching

Packet Switching is the method that is used to transfer data on the Internet. Within a packet switching network, the data that comes from the machine is broken up into small chunks. Each of the chunks includes the addresses of both the destination and the origin. It enables chunks of data from all different sources to intermingle with one another on the same lines, furthermore it can be sorted and re-directed along alternative routes. Through this many people can access the same lines all at the same time.

PAD

Packet assembler-disassembler.

PCB

Printed circuit board.

PDA

Personal Digital Assistants.

PDS

Premises distribution system.

Personal numbers

A user that has a personal number has the ability to instruct that all calls to that number can be diverted to any of the other numbers (including a voice mail box).

PHY

Physical-layer protocol.

PMD

Physical-layer media-dependent.

Point-of-presence (POP)

A POP is an actual physical location that exists within a LATA that is established as an IXC establishes for the exact purpose of gaining access to BOC/LEC networks that reside within the LATA. This is done using LEC provided access services. IXC may possibly have more than one POP that operates within a LATA and that POP may also support private and public, non-switched and switched services.

POT

Point of termination.

PPSN

Public packet switched network.

Private Branch Exchange (PBX)

A PBX exists as a premises switching system. This serves as a commercial or a government organization. It is usually located on that organization's premises. These PBXs provide telecommunications services on the campus or premises, (for example; internal calling and also other services)They also provide access to both private and public telecommunications network services.

Private Exchange Master List (PXML)

This lists all of the permissible uses of and the attachments to a PABX.

Private Network

A private network exists as a network that is made up of circuits and, even sometimes, switching equipment. It is used exclusively for one organization.

PRI

Primary rate interface.

Protocols

Protocols exist as strict procedures for the initiation, termination and maintenance of data communications. Protocols actually define the syntax (formats, arrangements and patterns of bytes and bits) and also the semantics ( information context or system control or meaning of patterns of bits or bytes) of the exchanged data. It also qualifies numerous other characteristics (for example: data rates, timing, etc.).

PSN

Packet switched network.

PSTN

Public switched telecommunications network.

PTO

Public Telecommunications Operator (e.g., Cable & Wireless or BT).

Public Switched Telephone Network (PSTN)

A Public Switched Telephone Network (PSTN) exists as those sections of the LEC and IXC networks that operate to provide telephone network services that are public switched.

PVC

Permanent virtual circuit.