P

PACS:

Personal Access Communication System; a digital cordless technology developed initially 

by Bell Labs in the US, PACS was designed to compete with DECT


PACS
Personal Access Communication System; a digital cordless technology developed initially 

by Bell Labs in the US, PACS was designed to compete with DECT

Packet switching
A communication system wherein the information is transmitted in packets of a set size. 

These packets have address headers and find their way to their destination by the most 

efficient route through the network. Compared to circuit switching where a connection 

is occupied until the traffic exchange is completed, packet switching offers 

considerable efficiencies as connections can be used by a number of users 

simultaneously

PAMR
Public Access Mobile Radio; Commercial service using trunking techniques in which 

multiple groups of users can set up their own closed systems within a shared public 

network

PAP
Public Access Profile; a DECT term

PCH
Paging Channel; downlink only, the MS is informed of incoming calls by the BTS via the 

PCH

PCM
Pulse Code Modulation; the standard digital voice format at 64kbit/s

PCMCIA
Personal Computer Memory Card Interface Association the body responsible for defining 

the standards and formats for memory expansion cards for laptop computers and PDAs. Now 

extended to cover cards for mobile phones

PCN
Personal Communications Network; a designation initially used in the UK to refer to 

networks operating in the 1800MHz band (see also DCS1800). No longer in use

PCS 1900
Personal Communications Systems 1900MHz; the terminology used in the US to describe the 

new digital networks being deployed in the 1900MHz band; rarely used today

PCU
Packet Control Unit; an element in a GPRS/UMTS network

PDA
Personal Digital Assistant

PDC
Personal Digital Communications; a digital cellular technology developed and deployed 

uniquely in Japan. A TDMA technology, PDC is incompatible with any other digital 

cellular standard

PEDC
Pan European Digital Communications; A designation occasionally used in the early 

1990’s to describe GSM. No longer in use

Penetration
The percentage of the total population which owns a mobile phone

PHS / PHP
Personal HandyPhone System/Phone; a digital cordless technology developed in Japan 

which achieved great success. Deployed by NTT DoCoMo and other Japanese operators PHS 

offered two-way communications, data services and Internet access and eventually won 

some 28 million customers. Now in decline as cellular’s wide area capabilities offer 

better service

PIN
Personal Identifier Number

PKI
Public Key Infrastructure

PLMN
Public Land Mobile Network; any cellular operator’s network

PMR
Private Mobile Radiocommunications; two-way radio technology widely used for despatch 

and delivery services, taxi companies and the like. See TETRA

POCSAG
Post Office Code Standardisation Group; a now defunct industry grouping which 

standardised pager addressing systems

PoP
Points of Presence; a method of measuring the value of a cellular licence; the 

approximate number of potential customers within a geographical area

POTS
Plain Old Telephone Service

PROM
Programmable Read Only Memory

PSK
Phase Shift Keying

PSRCP
Public Safety Radio Communications Project; an initiative by the UK Government to 

standardise all emergency services communications on to a single digital technology 

(see TETRA)

PSDN
Public Switched Data Network

PSPDN
Public Switched Packet Data Network

PSTN
Public Switched Telephone Network

PSU
Power Supply Unit

PTO
Public Telecommunication Operator

PTT
Posts, Telephone and Telegraph Administration

PTT
Push-to-Talk; a feature of PMR systems

PWT
Personal Wireless Telecommunications; a variant of DECT developed for use in the USA


PCN
Personal Communications Networks; an outdated term for GSM services in the 1800MHz band

PDA
Personal Digital Assistant; a sophisticated handheld device with advanced display 

facilities and a range of business-oriented software programs

Phone book
A list of personal names and numbers stored in a mobile phone’s internal memory or in 

the SIM card. These numbers can be called by accessing the appropriate memory and 

making a single key stroke

PIN
Personal Identity Number; a number, usually four digits, that must be keyed into a 

mobile phone to make it work. A security measure to prevent unauthorised usage

P-Java (Personal Java) a Java API and specification for running Java applications on 

small devices. 

Packet a piece of data transmitted over a packet-switching network such as the Internet 

or wireless Internet; a packet includes not just data but also its destination. 

Packet Switching a type of communication that splits information into “packets” of data 

for transmission. This is efficient, as it only uses radio spectrum when it’s actually 

sending something, rather than keeping an open channel at all times (as is done in 

circuit switching). Packet switching is a core component to 3G technology. 

Passive Matrix Display an LCD technology that uses a grid to supply the charge to each 

particular pixel on the display. An STN screen has a slower refresh rate than a TFT 

screen, but it’s cheaper. Also called a SuperTwist Nematic of STN display. 

PC Card (PCMCIA) a removable, credit-card sized devices that may be plugged into slots 

in PCS and wireless communication devices to provide fax or modem functions or network 

cards. 

PCMCIA (Personal Computer Memory Card International Association) a group of hardware 

manufacturers and vendors responsible for developing standards for PC Cards (also 

called PCMCIA cards.) 

PCN:

also known as DCS 1800 or GSM 1800, PCN is a term used to describe a wireless 

communication technology in Europe and Asia. 

PDA (personal digital assistant) a portable, handheld computing device that acts as an 

electronic organizer. PDAs are typically used for managing addresses, appointments, 

to-do lists and notes, but some newer models support wireless Internet access, e-mail, 

and other interactive applications. Also referred to as Handheld Computers. PDAs come 

in two major flavors - Palm and Pocket PC. 

PIN (Personal Identification Number) a numeric code or password that may be required by 

a service provider in order to make outgoing calls or obtain access to certain 

applications and data. This code is always associated to a SIM card, not a phone and is 

designed to help guard against cellular fraud. 

PTT (Push-To-Talk) a two-way communication service that works like a “walkie talkie”. 

This feature, found on Motorola iDEN phones from Nextel and Telus Mobility’s Mike, 

allow communication in only direction at a time unlike a cell phone that allows for 

simultaneous conversations. New PTT systems are now being introduced that use VoIP 

technology to provide PTT service digitally over 3G data networks

PUK (Personal Unblocking Code) used to unblock a blocked SIM card, this code is given 

during the subscription of a phone

PWR:
represents the on/off (power) key on some wireless devices.
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