Cisco Systems ATA187I1ARF manual Pbx, GL-3

	Glossary
FXO	Foreign Exchange Office. An FXO interface connects to the public switched phone network (PSTN)
	central office and is the interface offered on a standard phone. Cisco FXO interface is an RJ-11
	connector that allows an analog connection at the PSTN central office or to a station interface on a
	PBX.
FXS	Foreign Exchange Station. An FXS interface connects directly to a standard phone and supplies ring,
	voltage, and dial tone. Cisco's FXS interface is an RJ-11 connector that allows connections to basic
	phone service equipment, keysets, and PBXs.
G
G.711	Describes the 64-kbps PCM voice coding technique. In G.711, encoded voice is already in the correct
	format for digital voice delivery in the PSTN or through PBXs. Described in the ITU-T standard in its
	G-series recommendations.

G.723.1

G.729A

Describes a compression technique that can be used for compressing speech or audio signal components at a very low bit rate as part of the H.324 family of standards. This Codec has two bit rates associated with it: 5.3 and 6.3 kbps. The higher bit rate is based on ML-MLQ technology and provides a somewhat higher quality of sound. The lower bit rate is based on CELP and provides system designers with additional flexibility. Described in the ITU-T standard in its G-series recommendations.

Describes CELP compression where voice is coded into 8-kbps streams. There are two variations of this standard (G.729 and G.729 Annex A) that differ mainly in computational complexity; both provide speech quality similar to 32-kbps ADPCM. Described in the ITU-T standard in its G-series recommendations.

gateway	A gateway allows SIP or H.323 terminals to communicate with terminals configured to other protocols
	by converting protocols. A gateway is the point where a circuit-switched call is encoded and
	repackaged into IP packets.

H

H.323	H.323 allows dissimilar communication devices to communicate with each other by using a standard
	communication protocol. H.323 defines a common set of CODECs, call setup and negotiating
	procedures, and basic data transport methods.

I

ICMP Internet Control Message Protocol

	Cisco ATA 187 Analog Telephone Adaptor Administration Guide for SIP (Version 1.0)
OL-21862-01		GL-3