Contents

• Glossary

Glossary

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This table contains definitions for terms used in this document.

H.225	Call Signaling and RAS in H.323 VoIP Architecture; an ITU standard in the H.323 VoIP architecture. Governs session establishment and packetization where the transmission path includes one or more packet-based networks that provide non guaranteed quality of service.
H.245	Control Protocol for Multimedia Communication; an ITU standard in the H.323 VoIP architecture. Governs control signaling and endpoint control.
H.323	Standard for packet-based video, audio, and data conferencing. Umbrella standard that describes the architecture of a conferencing system and refers to other standards (H.245, H.225.0, and Q.931) to describe its actual protocols. Defines a common set of codecs, call setup and negotiating procedures, and basic data-transport methods that allow dissimilar communication devices to communicate with each other.
CAS	Channel-associated signaling. The transmission of signaling information within the voice channel. CAS signaling often is referred to as robbed-bit signaling because user bandwidth is being robbed by the network for other purposes.
endianness	Way of expressing the order in which a computer processor stores and transmits the individual bytes of a multiple-byte item of data. Big-endian processors store the most significant byte at the memory location with the lowest address. Little-endian processors store it at the location with the highest address. Processors from different manufacturers vary in endianness (for example, Intel x86 uses little and PowerPC uses big). Difficulties can potentially arise when data moves between systems of different endianness. For example, the IP address 10.1.1.13 could be interpreted as 13.1.1.10.
JTAPI	Java Telephony Application Programming Interface. A call-control model developed by Sun Microsystems.
MGCP	Media Gateway Control Protocol. Protocol that enables media gateway controllers and media gateways to communicate for call control on VoIP networks.
Q.931	ISDN Network Layer Protocol for Signaling; an ITU standard. Governs layer 3 ISDN call establishment, maintenance, and termination of logical network connections between two devices.
SCCP	Skinny (or Simple) Client Control Protocol. Cisco-proprietary protocol that defines call-connection methods and signaling between IP phones and a router. Allows IP phones to coexist in an H.323 environment. Savings in memory size, processor power, and complexity makes the protocol desirable.
SDP	Session Description Protocol. Protocol for describing multimedia sessions for the purposes of session announcement, session invitation, and other forms of multimedia session initiation.
SIP	Session Initiation Protocol. Protocol, developed as an alternative to H.323, that equips platforms to signal the setup of voice and multimedia calls over IP networks.

Note	See Internetworking Terms and Acronyms for terms not included in this glossary.