O/E/O Optic-Electronic-Optic conversion
OA Ordered Aggregate
OADM Optical Add-Drop Multiplexer
OAM Operations and Maintenance
OCC Optical Connection Controller
OCh Optical Channel
O-D Origin-Destination
OIF Optical Internetworking Forum
OMG Object Management Group
OMP Optimised MultiPath
OMS Optical Multiplex Section
OS Operations System
OSI Open System Interconnection
OSPF Open Shortest Path First
OSS Operation Support System
OTN Optical Transport Network
OTS Optical Transmission Section
overlapPartit overlapping Partitions
OXC Optical Cross-Connect
P Provider
PAWS Protect Against Wrapped Sequences
PBS Peak Burst Size
PBX Private Branch Exchange
PC Personal Computer
PCBR Premium Constant Bit Rate
PCF Policy Control Function
PCM Pulse Code Modulation
P-CSCF Policy Call State Control Function
PDB Per Domain Behaviour
PDF Probability Density Function
PDP Packet Data Processor
Packet Data Protocol (UMTS)
PDR Peak Data Rate
PE Provider Edge
PEP Policy Enforcement Point
PHB Per Hop Behaviour
PI Policy Interface
PIB Policy Information Base
PIM-DM Protocol-Independent Multicast – Dense Mode
PIM-SM Protocol-Independent Multicast – Sparse Mode
PIN Policy-Ignorant Node
PIR Peak Information Rate
PL Packet Length
PLC Packet Loss Concealment
PLMN Public Land Mobile Network
PMC Premium Mission Critical
PMM Premium MultiMedia
PNO Public Network Operator
POP Point Of Presence
POS Packet Over SDH
POTS Plain-Old Telephony Service
PPP Point-to-Point Protocol
PRC Policy Rule Class
PRP Policy Retrieval Point
PS Packet Switched
PSC Per hop behaviour Scheduling Class
PSH Push
PSPWG Packet Switching Protocols Working Group
PSTN Public Switched Telephone Network
PVBR Premium Variable Bit RateQC Quality Category
QCS Quality Class Specification
QoS Quality of Service
QPIM QoS Policy Information ModelR&D Research and Development
RAB Radio Access Bearer
RADIUS Remote Authentication Dial-In User Service
RAM Random Access Memory
RAN Radio Access Network
RAP Resource Allocation working group (IETF)
RAR Resource Allocation Request
Rec. Recommendation
RED Random Early Detection
Random Early Discard
REP Report
REQ Request
RFC Request for Comments
RIB Routing Information Base
RIO Random Early Detection with In/Out bit
RIP Routing Information Protocol
RLC Radio Link Control
RLR Receive Loudness Rating
RM-ODP Reference Model for Open Distributed Processing
RNC Radio Network Controller
ROA Recognised Operating Agencies
RST ResetNPL Network Parameters Level
NPP Network Performance Parameters
NRT Non-Real Time
NTA Norwegian Telecommunications Administration
NTP Network Time Protocol
NU Network User