Glossary Terms - "P"

Packet
An aggregation of data and controls, in an ordered group, transmitted through a network, as the subset of a larger message.

A group of binary digits switched as a whole - for instance, a file transfer over a packet switched network would require many steps. These steps are: 1) the data file would be broken down into smaller "packets" of information 2) each packet of information is assigned a code that enables it to be sent to the correct location and, once at that location, for the network to reassemble the packets of information into their original form.

Packet Switched Network
A digital data transmission network that uses packet switching technology.

Packet Switching
A data transmission technique where user information is segmented and routed in discrete data envelopes called packets, each with its own appended control information for routing, sequencing, and error checking. It allows a communications channel to be shared by many users, each using the circuit only for the time required to transmit a single packet.

Refers to protocols in which messages are divided into packets before they are sent. Each packet is then transmitted individually and can even follow different routes to its destination. Once all the packets forming a message arrive at the destination, they are recompiled into the original message.

Most modern Wide Area Network (WAN) protocols, including TCP/IP, X.25, and Frame Relay, are based on packet-switching technologies. In contrast, normal telephone service is based on a circuit-switching technology, in which a dedicated line is allocated for transmission between two parties. Circuit-switching is ideal when data must be transmitted quickly and must arrive in the same order in which it's sent. This is the case with most real-time data, such as live audio and video. Packet switching is more efficient and robust for data that can withstand some delays in transmission, such as e-mail messages and Web pages.

Paging
A service designed to deliver numeric or alphanumeric messaging to a person whose location is uncertain - paging services make use of radio communications.

PBX (Private Branch Exchange)
Short for private branch exchange, a private telephone network used within a business. Users of the PBX share a certain number of outside lines for making telephone calls external to the PBX. Dial is typically just 3 or 4 digits for internal calling.

PC
Personal Computer.

PCS. Personal Communications Services
New wireless services authorized by the FCC through spectrum auctions beginning in 1994.

Peer-to-Peer
A data exchange method in which two or more nodes can initiate communication with each other.

Permanent Virtual Circuit
A virtual circuit resembling a leased line (the invariant logical channel numbers allow it to be dedicated to a single user.)

PIC Code
An assigned Primary Interexchange Carrier Code. The carrier is selected by the customer and the service provider loads the code into the customer record.

PICC Code
Pre-assigned Interexchange Carrier Code.

Point-To-Point
Used to describe a circuit that connects two points directly. There are generally no intermediate processing nodes or computers, although there could be switching facilities (i.e., a phone line circuit that links two and only two logical entities.)

POP (Point of Presence)
A physical layer within a LATA at which an interLATA carrier establishes itself for the purpose of obtaining LATA access and to which the local exchange company provides access services. The point at which the local telephone company terminates subscribers’ circuits for long-distance dial-up or leased-line communications.

POTS. Plain Old Telephone Service
Traditionally, this is the term used to describe telephone lines that are connected to most residential and small business users. These lines are usually limited in the speed of data transmissions. PANS (Pretty Amazing New Stuff).

Premises Wiring
Wiring that connects separately housed equipment entities or system components to one another, or wiring that connects an equipment entity or system component to a telephone network interface, located at the customer’s premises and not within an equipment housing.

PRI (Primary Rate Interface)
A level of service for ISDN (in the U.S. 23 64 Kbps “B” channels for information transfer and 1 64 Kbps “D” channel for control and signaling.)

Price Cap Regulation
An obsolete and mostly disbanded form of regulation that places a ceiling and in some instances a floor on prices rather than attempting to assess costs and rates of return.

Private Line
Denotes the channel and channel equipment furnished to a customer as a unit for exclusive use, generally, with no access to or from the public switched telephone network. Also called leased line. Typically provisioned to provide point-to-point connectivity between two customer sites.

Private Network
A network that is designed for use exclusively by a person or organization and usually does not have points of access from users external to the company.

Proprietary System
See closed system.

Protocol
The rules of order by which a communications network is operated. Also the rules by which a specific data communications function must proceed.

PSTN (Public Switched Telephone Network)
The domestic telecommunications network commonly accessed by ordinary telephones, key systems, PBX trunks, and data access arrangements.

Public Network
Generically, a network operated by common carriers or telecommunications administrations for the purpose of providing circuit-switched, packet-switched, and leased-line circuits to the public.

PUC (Public Utility Commission)
The state regulatory administrative body that directs intrastate utilities, including telecommunications. Also known as Public Service Commission (PSC.)

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z