Glossary

glossary

A

ACOM

Term used in G.165, "General Characteristics of International Telephone Connections and International Telephone Circuits: Echo Cancellers." ACOM is the combined loss achieved by the echo canceller, which is the sum of the Echo Return Loss, Echo Return Loss Enhancement, and nonlinear processing loss for the call.

ADPCM

Adaptive differential pulse code modulation. Process by which analog voice samples are encoded into high-quality digital signals.

API

Application programming interface. Specification of function-call conventions that defines an interface to a service.

A
ACOM	Term used in G.165, "General Characteristics of International Telephone Connections and International Telephone Circuits: Echo Cancellers." ACOM is the combined loss achieved by the echo canceller, which is the sum of the Echo Return Loss, Echo Return Loss Enhancement, and nonlinear processing loss for the call.
ADPCM	Adaptive differential pulse code modulation. Process by which analog voice samples are encoded into high-quality digital signals.
API	Application programming interface. Specification of function-call conventions that defines an interface to a service.

B

BECN

Backward explicit congestion notification. Bit set by a Frame Relay network in frames travelling in the opposite direction of frames encountering a congested path.

B
BECN	Backward explicit congestion notification. Bit set by a Frame Relay network in frames travelling in the opposite direction of frames encountering a congested path.

C

Call leg

Segment of a call path. A logical connection between a telephone and a router, a router and a network, a router and a PBX, or a router and the PSTN using a session protocol. Each call leg corresponds to a dial peer.

CIR

Committed information rate. The average rate of information transfer a subscriber (for example, the network administrator) has stipulated for a Frame Relay PVC.

CODEC

Coder decoder. Device that typically uses pulse code modulation to transform analog signals into a digital bit stream, and digital signals back into analog. In VoIP, it specifies the voice coder rate of speech for a dial peer.

C
Call leg	Segment of a call path. A logical connection between a telephone and a router, a router and a network, a router and a PBX, or a router and the PSTN using a session protocol. Each call leg corresponds to a dial peer.
CIR	Committed information rate. The average rate of information transfer a subscriber (for example, the network administrator) has stipulated for a Frame Relay PVC.
CODEC	Coder decoder. Device that typically uses pulse code modulation to transform analog signals into a digital bit stream, and digital signals back into analog. In VoIP, it specifies the voice coder rate of speech for a dial peer.

D

Dial peer

Software object that ties together a voice port and a local telephone number (local dial peer or POTS dial peer) or an IP address and a remote telephone number (remote dial peer or VoIP dial peer). Each dial peer corresponds to a call leg.

DLCI

Data-link connection identifier. Value that specifies a PVC or SVC in a Frame Relay network.

DSP

Digital signal processor. DSP segments the voice signal into frames and stores in voice packets.

DTMF

Dual tone multifrequency. Use of two simultaneous voice-band tones for dialing (such as touch tone).

E

E.164

International public telecommunications numbering plan. A standard set by ITU-T that addresses telephone numbers.

E&M

E&M interface uses a RJ-48 telephone cable to connect remote calls from an IP network to PBX trunk lines (tie lines) for local distribution. It is a signaling technique for two-wire and four-wire telephone and trunk interfaces.

D
Dial peer	Software object that ties together a voice port and a local telephone number (local dial peer or POTS dial peer) or an IP address and a remote telephone number (remote dial peer or VoIP dial peer). Each dial peer corresponds to a call leg.
DLCI	Data-link connection identifier. Value that specifies a PVC or SVC in a Frame Relay network.
DSP	Digital signal processor. DSP segments the voice signal into frames and stores in voice packets.
DTMF	Dual tone multifrequency. Use of two simultaneous voice-band tones for dialing (such as touch tone).

E
E.164	International public telecommunications numbering plan. A standard set by ITU-T that addresses telephone numbers.
E&M	E&M interface uses a RJ-48 telephone cable to connect remote calls from an IP network to PBX trunk lines (tie lines) for local distribution. It is a signaling technique for two-wire and four-wire telephone and trunk interfaces.

F

Frame Relay

Industry standard for switched data link layer protocol that handles multiple virtual circuits using HDLC encapsulation between connected devices.

FXO

Foreign exchange office. The FXO interface uses a RJ-11 modular telephone cable to connect local calls to a PSTN central office or to PBX that does not support E&M signaling. This interface is used for off-premise extension applications.

FXS

Foreign exchange station. The FXS interface uses a standard RJ-11 modular telephone cable to connect directly to a standard telephone, fax machine, PBXs, or similar device, and supplies ring, voltage, and dial tone to the station.

F
Frame Relay	Industry standard for switched data link layer protocol that handles multiple virtual circuits using HDLC encapsulation between connected devices.
FXO	Foreign exchange office. The FXO interface uses a RJ-11 modular telephone cable to connect local calls to a PSTN central office or to PBX that does not support E&M signaling. This interface is used for off-premise extension applications.
FXS	Foreign exchange station. The FXS interface uses a standard RJ-11 modular telephone cable to connect directly to a standard telephone, fax machine, PBXs, or similar device, and supplies ring, voltage, and dial tone to the station.

H

H.323

ITU-T standard that describes packet-based video, audio, and data conferencing.

HDLC

High-Level Data Link Control. A data link layer protocol that specifies a data encapsulation method on synchronous serial links using frame characters and checksums.

H
H.323	ITU-T standard that describes packet-based video, audio, and data conferencing.
HDLC	High-Level Data Link Control. A data link layer protocol that specifies a data encapsulation method on synchronous serial links using frame characters and checksums.

I

ITU-T

International Telecommunications Union-Telecommunications standardization section.

I
ITU-T	International Telecommunications Union-Telecommunications standardization section.

M

Multilink PPP

Multilink Point-to-Point Protocol. This protocol defines a method of splitting, recombining, and sequencing datagrams across multiple logical data links.

M
Multilink PPP	Multilink Point-to-Point Protocol. This protocol defines a method of splitting, recombining, and sequencing datagrams across multiple logical data links.

N

NANP

North American Numbering Plan. The format in North America is 1Nxx-Nxx-xxxx, with N = digits 2 through 9 and x = digits 0 through 9.

N
NANP	North American Numbering Plan. The format in North America is 1Nxx-Nxx-xxxx, with N = digits 2 through 9 and x = digits 0 through 9.

P

PBX

Private branch exchange. Privately-owned central switching office.

PCM

Pulse code modulation. Transmission of analog information in digital form through sampling and encoding the samples with a fixed number of bits.

PLAR

Private line auto ringdown. PLAR connection associates a peer directly with an interface. This type of service results in a call attempt to some particular remote endpoint when the local extension is taken off-key.

POTS

Plain old telephone service. Basic telephone service supplying standard single-line telephones, telephone lines, and access to the public switched telephone network.

POTS dial peer

Dial peer connected via a traditional telephony network. A software object that ties together a voice port and the telephone number of a device attached to the port (also called local dial peer).

PSTN

Public Switched Telephone Network. PSTN refers to the local telephone company. Sometimes called plain old telephone service (POTS).

PVC

Permanent virtual circuit. Virtual circuit that is permanently established and is torn down in situations where certain virtual circuits must exist all the time. PVCs save bandwidth associated with circuit establishment.

P
PBX	Private branch exchange. Privately-owned central switching office.
PCM	Pulse code modulation. Transmission of analog information in digital form through sampling and encoding the samples with a fixed number of bits.
PLAR	Private line auto ringdown. PLAR connection associates a peer directly with an interface. This type of service results in a call attempt to some particular remote endpoint when the local extension is taken off-key.
POTS	Plain old telephone service. Basic telephone service supplying standard single-line telephones, telephone lines, and access to the public switched telephone network.
POTS dial peer	Dial peer connected via a traditional telephony network. A software object that ties together a voice port and the telephone number of a device attached to the port (also called local dial peer).
PSTN	Public Switched Telephone Network. PSTN refers to the local telephone company. Sometimes called plain old telephone service (POTS).
PVC	Permanent virtual circuit. Virtual circuit that is permanently established and is torn down in situations where certain virtual circuits must exist all the time. PVCs save bandwidth associated with circuit establishment.

Q

QoS

Quality of service. Measure of performance for a transmission system that reflects its transmission quality and service availability.

Q
QoS	Quality of service. Measure of performance for a transmission system that reflects its transmission quality and service availability.

R

RSVP

Resource Reservation Protocol. A network protocol that enables routers to reserve the bandwidth necessary for reliable performance.

RTCP

RTP Control Protocol. A protocol that monitors the QoS of an IPv6 RTP connection and conveys information about the on-going session.

RTP

Real-Time Transport Protocol. RTP is designed to provide end-to-end network transport functions for applications transmitting real-time data, such as audio, video, or simulation data, over multicast or unicast network services.

R
RSVP	Resource Reservation Protocol. A network protocol that enables routers to reserve the bandwidth necessary for reliable performance.
RTCP	RTP Control Protocol. A protocol that monitors the QoS of an IPv6 RTP connection and conveys information about the on-going session.
RTP	Real-Time Transport Protocol. RTP is designed to provide end-to-end network transport functions for applications transmitting real-time data, such as audio, video, or simulation data, over multicast or unicast network services.

S

SNMP

Simple Network Management Protocol. SNMP provides a means to monitor and control network devices, and to manage configurations, statistics collection, performance, and security.

SVC

Switched virtual circuit. Virtual circuit that is dynamically established on demand and that is torn down when transmission is complete.

S
SNMP	Simple Network Management Protocol. SNMP provides a means to monitor and control network devices, and to manage configurations, statistics collection, performance, and security.
SVC	Switched virtual circuit. Virtual circuit that is dynamically established on demand and that is torn down when transmission is complete.

T

Trunk

Service that provides quasi-transparent connections between two PBXs, a PBX and a local extension, or some other combination of telephony interfaces to be permanently conferenced together by the session application and signaling passed transparently through the IP network.

T
Trunk	Service that provides quasi-transparent connections between two PBXs, a PBX and a local extension, or some other combination of telephony interfaces to be permanently conferenced together by the session application and signaling passed transparently through the IP network.

U

UDP

User Datagram Protocol. UDP is a simple protocol that exchanges datagrams without acknowledgments or guaranteed delivery, requiring that error processing and retransmission be handled by other protocols.

U
UDP	User Datagram Protocol. UDP is a simple protocol that exchanges datagrams without acknowledgments or guaranteed delivery, requiring that error processing and retransmission be handled by other protocols.

V

VIC

Voice interface card. VICs install in a slot in the router, and provide the connection to the telephone equipment or network.

VoIP

Voice-over-IP, a feature that carries voice traffic, such as telephone calls and faxes, over an IP network, simultaneously with data traffic.

VoIP dial peer

Software object that ties together an IP address and a telephone number at a remote site reached over the IP network (also called remote dial peer).

VPM

Virtual voice-port module.

VTSP

Voice telephony service provider.

V
VIC	Voice interface card. VICs install in a slot in the router, and provide the connection to the telephone equipment or network.
VoIP	Voice-over-IP, a feature that carries voice traffic, such as telephone calls and faxes, over an IP network, simultaneously with data traffic.
VoIP dial peer	Software object that ties together an IP address and a telephone number at a remote site reached over the IP network (also called remote dial peer).
VPM	Virtual voice-port module.
VTSP	Voice telephony service provider.

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glossary