Glossary: Glossary

3GPP

Third Generation Partneship Project (ETSI)

AAA

Authentication, Authorization, Accounting

ABNF

Augmented Backus-Naur Form

ADSL

Asymmetric Digital Subscriber Line

AGC

Automatic Gain Control

ALG

Application Level Gateway

B2BUA

Back to Back User Agent. See also the definition by wikipedia.

Codec

Algorithm used to encode and decode multi-media data (voice, vide) in format suitable for transport in the Internet. See also: G.711, PCM

G.723.1

6.4/5.3 kbps MP-MLQ codec (low quality, low bandwidth, high processor load due to the compression)

G.726

40/32/24/16 ADPCM codec (good quality, medium bandwidth, low processor load)

G.728

16 kbps LD-CELP codec (medium quality, medium bandwidth, very high processor load)

G.729

8 kbps ACELP codec (medium quality, low bandwidth, high processor load)

GSM

Global System for Mobile communications

iLBC

internet Low Bitrate Codec

CPL

Call Processing Language, an XML based language that can be used to describe and control processing of calls in VoIP systems.

CPS

Calls Per Second

DIAMETER

IETF protocol that can be used for authentication, authorization, and accounting purposes. Successor of RADIUS. See also: RADIUS

DND

Do Not Disturb

DTMF

Dual Tone Multi-Frequency encoding of numbers. See also: VoIP

ETSI

European Telecommunications Standards Institute

G.711

64 kbps PCM half-duplex codec (high quality, high bandwidth, minimum CPU load) See also: Codec

GLP

Gateway Location Protocol

ICMP

Internet Control Message Protocol.

IEEE

Institute of Electrical and Electronic Engineers

IETF

Internet Engineering Task Force, the Internet standards body. See also: IAB, IANA, IESG, SIMPLE, SIPPING

BOF

Birds of a Feather. The term for IETF interest groups.

IAB

Internet Architecture Board, a group of people overseeing the technical aspects of the IETF/IESG See also: IANA, IESG, IETF

IANA

Internet Assigned Number Authority See also: IAB, IESG, IETF

IESG

Internet Engineering Steering Group See also: IAB, IANA, IETF

SIMPLE

Extensions of SIP for Instant Messaging and Presence, also a working group name in the IETF See also: IETF, SIP-related

SIPPING

Session Initiation Protocol Project Investigation, an IETF working group. See also: IETF

IMPP

Instant Messaging and Presence Protocol

IMS

IP Multimedia System

C-BGF

Core Border Gateway Function. (More description needed).

HSS

Home Subscriber Server. This is the server containing database of subscriber related data. See also: AUC, HLR

AUC

Authentication Center. (More description needed). See also: HSS

HLR

Home Location Register. (More accurate description needed). See also: HSS

I-BCF

Interconnect Border Control Function. (Do you know more ? Then please add more accurate description).

I-BGF

Interconnect Border Gateway Function. (More description needed).

I-CSCF

Interrogating Call Session Control Function. This is the element in the home network that determines the S-CSCF the UE should talk to. This is achieved by querying the Home Subscriber Server (HSS).

P-CSCF

The Proxy Call Session Control Function. This is the SIP proxy that UE will contact. This element can be either in home or in visited network. This element ensures that messages from UE are passed to correct home network of the UE.

S-CSCF

Serving Call Session Control Function. This is the element in the home network that registers users and provides services to them.

IPT

Internet Protocol Telephony

ISDN

Integrated Services Digital Network

ISP

Internet Service Provider

ITSP

Internet Telephony Service Provider

ITU

International Telecommunication Union

IVR

Interactive Voice Response

JTAPI

Java Telephony API

LDAP

Lightweight Directory Access Protocol

MGCP

Media Gateway Control Protocol

NAPT

Network Address and Port Translation See also: NAT

NAT

Network Address Translator See also: NAPT

PBX

Packet Branch Exchange

PCM

Pulse Code Modulation See also: Codec

POTS

Plain Old Telephone System

PSTN

Public Switched Telephone Network

PTT

Push To Talk

RADIUS

IETF protocol for authentication, authorization, and accounting. See also: DIAMETER

repository

A code repository system like CVS and subversion is a central storage where all code and all versions are kept. iptel.org projects use both CVS and subversion. See http://en.wikipedia.org/wiki/Version_control_system

branch

A term used in code repositories to describe a separate code tree that was branched out from the main development tree (trunk) and is maintained separately. Typically, in preparation for a new code release, a release branch is created. The main tree (trunk) can thus be used to introduce new code without affecting the release. The release branch is later used for creating bug fix releases.

head

The head of a given branch is (technically) the latest checked in version of the code (and not an earlier revision/version). However, the term head is sometimes also used interchangably with trunk.

tag

A tag is readable name for a given revision/version of a repository trunk or branch. Normally a tag is created when you want to have an easy to remember name for the code as it is at a given point. This means that you later can easily checkout the code using the tag and get the exactly like it was at the time you created the tag. See also: branching

trunk

The main development where all new changes are added and where developers do their stuff is referred to as the trunk.

RSVP

Resource Reservation Setup Protocol

RTP

Real-time Transport Protocol, an IETF protocol that can be used to carry multi-media data over the Internet. See also: RTCP

RTCP

Real-time Transport Control Protocol See also: RTP

RTSP

Real Time Streaming Protocol

SRTP

Secure Real-time Transport Protocol

RTPproxy

Real-time Transport Protocol proxy server.

S/MIME

Secure Multipurpose Internet Mail Extensions

SCTP

Stream control Transmission Protocol, a transport protocol designed specificaly for signalling.

SDP

Session Description Protocol, simple plain text document (usually in the body of SIP messages) that describes the capability of an internet end point.

SEMS

SIP Express Media Server: flexible framework for media-oriented applications.

SER

SIP Express Router, fast and flexible SIP server.

SERctl

The cmd-line tools for administrators of SER based SIP servers.

SERweb

The WWW interface for administrators of SER based SIP servers.

SIP-related

Session Initiation Protocol related terms. See also: SIMPLE

branching

A proxy server can send each SIP request to multiple destinations (either using forking or sending the request sequentially). Each downstream SIP request is sent on its own branch (which is represented by its own UAC in the proxy server). See also: tag, UAC

CSeq

Sequential number of SIP requests within a SIP dialog. The number is used to detect out of order requests and retransmissions.

dialog

Dialog is a relationship between two or more SIP user agents that persist for the duration of a call (or session). Dialog is typically created by INVITE request and destroyed when the user agent receives BYE request. Dialogs are identified using the value of Call-ID header field, from tag, and to tag (thus SIP messages having same Call-ID, from tag, and to tag belong to the same dialog).

downstream

The direction of SIP requests (that is from UAC to UAS). See also: UAC, UAS, upstream

forking

A SIP proxy server may send single SIP message to multiple destinations, this process is called "forking". See also: recursive

recursive

When a proxy server receives a negative reply for a request it previously forwarded, it may decide to forward the request again to another destination (such as voicemail server to store a message). This is called recursive (or sequential) forwarding. See also: forking

Request-URI

The URI representing the intended destination of SIP request. Every SIP request contains the Request-URI on the first line of the message header. See also: URI

retransmission

SIP messages are often transferred by means of unreliable transport protocols such as UDP. SIP implementations would send SIP request again if receives no reply within a period of time to compensate for possible packet losses that can occur in the network.

stateful

Proxy or user agent that keeps transaction state in memory while processing SIP messages. Transaction-stateful implementations can associate SIP responses to SIP requests and can absorb retransmissions.

stateless

Very simple user agent or proxy server. Stateless proxies or user agents keep no state in memory while processing SIP messages and thus are not able to correlate SIP messages.

transaction

A collection of SIP messages which includes initial SIP request and all associated SIP replies.

UAC

User Agent Client. The (logical) part of SIP implementation which generates SIP requests and receives and processes SIP responses. See also: branching, downstream, UAS, upstream

UAS

User Agent Server. Logical part of SIP implementation which receives SIP requests and generates SIP responses. See also: downstream, UAC, upstream

upstream

The direction of SIP responses (that is from UAS to UAC). See also: downstream, UAC, UAS

URI

Uniform Resource Identifier. A string representing a resource in the Internet. See also: Request-URI

SMTP

Simple Mail Transport Protocol

TTL

Time To Live, the maximum number of hosts that any given packet or message is allowed to pass before it will be discarded.

VoIP

Voice over IP See also: DTMF

ADPCM

Adaptive Differential Pulse Code Modulation

CDR

Call Detail Record