[P]

P factor – Grade of service which describes the percentage of blocked calls. For example, P.10 means that 10 percent of all calls were blocked; P.01 means that 1 percent of all calls were blocked.

Packet assembler/disassembler (PAD) – (1) A non-adjustable resistance network used to insert transmission loss into a circuit. (2) To fill a block with dummy data, usually zeros or blanks.
PAD character – A fill character inserted when insufficient data characters are present to satisfy a field length requirement.

Parity - A constant state or equal value.

Parity bit – A check character or bit appended to an array of binary digits to make the sum of the digits, including the check bit, always odd or always even.

Parity checking – One of the oldest error checking techniques. Character bit patterns are forced into parity (total number of bits odd or even) by adding a 1 or 0 bit as appropriate, as they are transmitted. The parity (odd or even) is then verified upon receipt by the receiving device.

Patch – (1) To make an improvised modification (2) To change a software routine in a rough or expedient way. (3) A temporary electrical connection.

PBX trunk – Connects a customer’s PBX to another PBX, central office (CO), remote CO or Sprint switch. (See Private Branch exchange).

Percent denial – (1) A measure of the grade of service provided on a dial access circuit group; the average percentage of attempts blocked or denied due to a busy condition during the busy hour.

Peripheral - Any input/output device such as a printer or modem that is not a part of the main computer.

Personal identification number (PIN) – The last two digits of an authorization code that identify the caller. [The 14-digit number on a Sprint FONCARD that uniquely identifies the card holder.]

Phase jitter – A random distortion of signal lengths. [Phase jitter interferes with interpretation of information by changing the timing.]
phosphor – Material which coats the back side of a CRT screen.

Physical layer – Within the OSI model, lowest level of network processing below the link layer that is concerned with the electrical, mechanical and handshaking procedures over the interface that connects a device to a transmission medium (example, RS-232-C).

Picture element (pixel) – (1) A single dot on a computer display. (2) The smallest discrete part of a video image, the size of which is controlled by an analog-to-digital conversion sampling process. [The more picture elements per line, the higher the resolution of the image.]

Pixel - Single dot on a computer display, short for picture element.

Point-of-presence (POP) - The physical location within a LATA (local access and transport area) where an interexchange carrier’s circuits connect with the lines of the local telephone company serving that LATA.

Point-to-point circuit – A private communications link between two terminations which does not connect with a public telephone system.

Polar keying - Technique of current loop signaling in which electrical flow direction establishes the two-level binary code.

Polling – Process by which a computer checks the readiness of other units to transmit or receive signals and information.

Port - (1) Entrance or access point to a computer, multiplexer network or device where signals may be supplied, extracted or observed. (2) The place where a peripheral device is connected to a computer.

Postal, Telephone and Telegraph (PTT) – International administration, usually government controlled, which manages and operates postal and telecommunications services outside the country. Typically a monopoly operation.

PostScript – Page-description programming language developed by Adobe Systems; designed to handle the placement of text and graphics on a page. The same PostScript file can be transmitted to printers of varying resolutions.

Presentation layer - The OSI processing layer that provides services to the application layer, allowing it to interpret the data exchanged as well as structure data messages to be transmitted in a specific display and control format.

Preventive maintenance – Precautionary measures taken on a system to forestall failures by providing for systematic inspection, detection and correction of incipient problems before they develop into major defects.

Primary Directory Number(PDN) – your phone number. A PDN appears on the bottom button of an electronic phone, is the phone number assigned to a personal set. Dial 191 to determine the PDN if it is not marked.

Primary routing point - The switch designated as the control point for a long-haul telephone call.

Private automatic branch exchange (PABX) – Small, local, automatic telephone office serving extensions in a business complex and providing access to the public network.

Private automatic exchange (PAX) – Small, local, automatic telephone office, normally serving extensions in a business complex, typically without external lines to the public network.

Private branch exchange (PBX) – Small, local, telephone office – either manually or automatically operated – serving extensions in a business complex and providing access to the public domain.

Private line – (1) A point-to-point telephone line for the exclusive use of one party. (2) A leased, owned or otherwise dedicated channel.

Private Line Service Center (PLSC) – Sprint organization which manages and maintains private line services. Each department is staffed with experienced professionals and subject matter experts in Private Line installation, service and support.

Private use network – Two or more channels contracted for by a customer and restricted for use by that customer only.

Program - A series of instructions or statements assembled in a form acceptable to a computer and prepared to achieve a certain result.

Prospect profile - A detailed description of a potential customer; the profile generally includes financial, demographic, industry, job title and past buying history information.

Protocol - A set of formalized conventions governing the format and relative timing of message exchange in a communications network.

Protocol conversion – Process of translating communications formats and timing, which would otherwise be incompatible, into messages understood by the network. Performed by a dedicated device, a software package loaded onto an existing system or by a value-added (intelligent) network.

Public service commission (PSC) – A regulatory authority at state level.

Public switched network (PSN) – Any switching system that provides a circuit switched to many customers.

Public utility commission (PUC) – A regulatory authority at state level.

Pulse - (1) A signal that can be wholly described by a constant amplitude and the duration time. (2) Signal form typically used internally in computers, terminals and other business machines as well as in communications facilities.

Pulse code modulation (PCM) – Method of sampling information signals at regular intervals and transmitting the samples as a series of pulses in coded form which represent the amplitude of the information signal at that time.

Pulse modulation – Method of varying the amplitude, frequency or phrase of information-bearing signals into a series of pulses. [Typical methods involve modifying the amplitude (PAM), width or duration (PDM) or position (PPM). The most common pulse modulation technique in telephone work is pulse code modulation (PCM).]

Pulse-link repeater - A device used to magnify signals in a telephone circuit and re-transmit corresponding pulses to another signaling circuit.

Pushbutton dialing – Type of signaling which emits two distinct frequencies for each indicated digit. Synonym: dual tone multifrequency (DTMF).