GLOSSARY:Call Processing Language, Gatekeeper, Media Gateway Control Protocol

<< ANNEX B. IP Telephony Hardware/Software:Softphones, Hardphones, Gateways

[IP Telephony Cookbook] / Glossary

Glossary

CPL

See Call Processing Language.

Call Processing Language

An XML application to define rules for call processing (e.g., to route all calls to a cell phone during

lunchtime). Decisions can be made upon the calling party number or the called party number, date

or time - just to name a few, while actions usually include rejection or redirections of calls.

Extensible Markup Language

A standard methodology with formal syntax for adding information to a document relating to its

structure and/or content by applying identifiers for elements of information in a neutral way,

stored in a neutral form, independent of systems, devices and applications.

Gatekeeper

In the H.323 world, the gatekeeper provides several important functions. First, it controls access to

the network, allowing or denying calls and controlling the bandwidth of a call. Second, it helps with

address resolution, making possible e-mail-type names for end users, and converting these into the

appropriate network addresses. A gatekeeper also handles call tracking and billing and call signalling.

See Gatekeeper.

Gateway

A gateway is a communication instance that translates (call) data between different networks (e.g.,

IP and PSTN) or protocols. A signalling gateway translates between two or more signalling

protocols (like H.323 or SIP), while a media gateway usually performs transcoding of media

streams (e.g., G.711 to GSM).

Of course a gateway may as well combine all functionality described above.

See Gateway.

H.323

ITU standard for videoconferencing over packet-switched networks such as Internet.

Media Gateway Control Protocol

A protocol for IP Telephony that enables a calling party with a PSTN phone number to locate the

destination device and establish a session.

MGCP

See Media Gateway Control Protocol.

P.226

[IP Telephony Cookbook] / Glossary

PBX

See Private Branch eXchange.

PSTN

See Public Switched Telephone Network.

Private Branch eXchange

A device used by organisations to allow a single access number to offer multiple lines to outside

calling parties and to allow internal staff to share a range of external lines.

Public Switched Telephone Network

The worldwide voice telephone network.

QoS

See Quality of Service.

Quality of Service

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

availability.

Real-time 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.

RTP

See Real Time Protocol.

SIP

See Session Initiation Protocol.

Session Initiation Protocol

IETF standard for session initiation in multi-purpose communication systems.

Voice over IP

The transmission of voice over data networks that use the Internet Protocol (IP).

VoIP

See Voice over IP.

XML

See Extensible Markup Language.

P.227

[IP Telephony Cookbook] /

P.228

Table of Contents: