Polycom DOC2066F manual Pots

Appendix A: Glossary

Abbreviation/	Explanation
Term
Network Service	A collection of spans from a fixed service provider. Network
	services can be any of the following types:
	•	Private Network
	•	Public Utility, including:
		•	Long distance service
		•	Local service
		•	PTT
		• PBX; local switchboard leased line
Null modem	A serial cable designed to eliminate the need for
cable	communication equipment when two digital devices are
	directly connected to each other.
Port	One of 23 channels in a T1 PRI; one of 24 channels in a T1
	leased line; or one of 30 channels in an E1 PRI.
POTS	Plain Old Telephone System. The conventional analog
	telephone line.
PRI	Priority Rate Interface. An ISDN interface designed for high
	volume data communication. Consists of 23 B channels of 64
	Kbps each and one D channel of 64 Kbps. In Europe, the PRI
	line provides 30 B channels + one D channel.
QCIF	Quarter CIF. A video format with image size of 176x144 pixels
	that transmits 9.115 Mbps at 30 frames per second (a quarter
	of the capacity of CIF). See also CIF.
RS-232	A standard for serial interface connection.
SIP	Session Initiation Protocol. An application-layer protocol
	designed to work over IP networks.A SIP service defines the
	properties and the IP addresses of the SIP network
	components.
Span	An ISDN line or leased line. A span may be of either T1
	(United States) or E1 (Europe) type. Also called a circuit.
Switched 56 line	A line using protocols pre-dating the ISDN protocols; also
	called a robbed bit signaling line or a pre-ISDN line.

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