Asynchronous: With reference to video and data signals and devices: not being precisely in step, not of the same frequency, or not happening together in time.

ATM: Asynchronous Transfer Mode, a digital transmission system using 53-byte packets. ATM may be used for LANs and WANs.

Digital Signal: Signal represented by a sequence of binary bits representing ones and zeros.

DS1: The AT&T Bell System level 1 digital standard for systems operating at 1.544 Mbps and consisting of 24 DS-0 channels.

DS3: The AT&T Bell System level 3 digital standard for systems operating at 44.736 (45) Mbps.

DSL: Digital Subscriber Line, a generic term encompassing a family of moderate speed access using a subscriber's existing copper lines.

FCC (Federal Communications Commission): A US body regulating, approving and licensing radiated electromagnetic signals including broadcasting and telecommunications.

Full Duplex: A transmission system, together with its associated equipment, capable of simultaneously transmitting and receiving signals, as opposed to simplex (unidirectional) or half-duplex (one direction at a time) systems.

Frame Relay: A wide-area network protocol often transported over DS1 facilities. Latency can cause problems for videoconferencing.

IP: Internet Protocol, packet transmission standard for the transmission of data, voice, video and other information over the Internet.

ISDN: Abbreviation for Integrated Services Digital Network. An integrated digital network in which the same time-division switches and digital transmission paths are used to establish connections for different services.

ISDN BRI: ISDN Basic Rate Interface, 2B+D. In the US, B may equal 56- or 64-Kbps. The D or signaling channel is 16 Kbps.

ISDN PRI: ISDN North American Primary-Rate Interface, 23B+D ISDN interface.

Kbps (Kb/s): Kilobits (thousands of bits) per second.

KBps (KB/s): KiloBytes (thousands of bytes or octets) per second.

LAN: Local Area Network, usually used to connect workstations to a server or to each other.

Mbps (Mb/s): Megabits (millions of bits) per second.

MBps (MB/s): MegaBytes (millions of bytes or octets) per second.

OC1: Optical Carrier level 1: 51.84 Mbps.

OC3: Optical Carrier level 3: 155.52 Mbps.

PBX: Private Branch Exchange. A telephone/data switching system, usually located on customer premises and belonging to the user. In contrast to Centrex which is largely located on the common carrier's premises. Some modern PBXs provide effective switched digital interfaces for operation of switched 64/56 Kbps and ISDN videoconferencing.

POP: Point-Of-Presence, the physical common carrier location.

POTS: Jargon, Plain Old Telephone Service.

SONET: Synchronous Optical NETwork.

Synchronous: With reference to video and data signals and devices: being precisely in step, or happening together in time.

T-1: The AT&T Bell System level 1 digital transmission system operating at 1.544 Mbps (1.536 Mbps excluding framing). T1 is commonly used to refer to DS1.

TCP/IP: Transmission Control Protocol/Internet Protocol. Networking protocols providing communications across interconnected networks (including Internet and Intranets). The networks may incorporate diverse hardware architecture computers and various operating systems. TCP/IP includes communication, connection and routing standard protocols.

Virtual Private Network (VPN): Virtual Private Network. A network that appears to its users as a private network although it may be made up of both private and public segments. A VPN may provide bandwidth on demand or fixed bandwidth facilities.

VoDSL: Voice over Digital Subscriber Loop, techniques permitting transmission of telephony over DSL.

VoIP: Voice over Internet Protocol, a series of techniques permitting transmission of telephony over the Internet. Often makes use of ITU-T G.7xx audio compression recommendations.

Wide Area Network (WAN): A physical or logical network that provides data communications to a larger number of independent users than are usually served by a local area network (LAN) and is usually spread over a larger geographic area than that of a LAN.

SOURCE: HEI