Glossary

B

Bandwidth refers to the capacity to move information. In telecommunications, bandwidth is the width of a communications channel. In digital communications, bandwidth is measured in bits per second (bps).

Abbreviation for Bits per Second, which is the unit of measure for the speed of data communications. Virtually all digital transmission circuits from WANs to LANs to Internet are defined in bits per second.

C

Acronym for Compression/Decompression. A codec is a method of digital compression and decompression which enables you to send and receive audio and video. Internet Phone Release 5 supports several different codecs. Quality and video speed varies among the codecs. Available bandwidth and number of lost packets can also affect the quality.

Compression

Reduced form of the information, but not the information itself. Compression saves transmission time or capacity.

D

Acronym for Dual Tone Multi-Frequency, which describes push-button or touchtone dialing. Each push-button on the telephone makes a combination of one high frequency tone and one low frequency tone. From these tones, the Signal Processing Card determines the dialed number.

F

Full-Duplex

Simultaneous transmission in two directions. Using full duplex transmission, both parties can speak at the same time. Actually, no phone communications are really full-duplex on a point to point connection; the line switches direction so fast that you cannot tell the difference.

G

A gateway is an entrance and an exit into a communications network. For example, a gateway can bridge the PSTN (Public Switched Telephone Network) with the Internet, or an Intranet. It's the link which connects both communication mediums and allows telephone-to-telephone calls via the Internet.

H

The H.323 specification defines packet standards for terminals, equipment and services for multimedia communications over LANs.

Half-Duplex

Data transmission in two directions, but not at the same time (such as speakerphones and CB radios).

I

Interactive Voice Response

Interactive Voice Response, or IVR is a technology by which you can access functions of a remote computer by using the keypad on your telephone. For example, a company using IVR may greet a telephone call with a message like, ``Welcome to VocalTec Communications Ltd. For the sales department, please dial 1. For customer support, please dial 2... Please enter the phone number you wish to dial''..., etc. You respond to the message's prompts by pressing keys on your telephone's touch keypad.

The Internet is a worldwide network of many smaller networks and services, such as the World Wide Web, e-mail, FTP, Usenet, Gopher...etc.

Internet Telephony

Internet Telephony is a technology that lets you make voice phone calls over the Internet. VocalTec's Internet Phone uses this technology.

An IP address is a unique, 32-bit number for a specific TCP/IP host on the Internet. IP addresses are normally written in dotted decimal form such as 128.127.50.224. A host uses a fixed IP Address as identification by the other equipment in the Network.

A private network that uses Internet software and Internet standards like TCP/IP.

Acronym for Internet Service Provider, a for-profit organization supplying inter-connection between an Internet Access Point and end users. ISPs usually offer one or more methods for accessing the Internet, such as dial-up serial connections, ISDN, and T1.

L

Acronym for Local Area Network, a short distance data communications network that links together computers and peripheral devices (such as printers) under standard control.

M

Acronym for Multipurpose Internet Mail Extensions, a specification defining interchange of text in languages with different character sets and multimedia e-mail, supporting different computer systems that use Internet mail standards.

P

Packet Switching

Packet switching is a technology for sending data in packets through a network to a remote location. Transmitted data is subdivided into individual packets of data, each with its own unique identification and destination address. The packets reach their destinations through different routes, and may also arrive in a different order than how they were sent.

Acronym for Public Switched Telephone Network, the telephone network that connects all users.

Acronym for Point-to-Point Protocol, PPP is the Internet standard for transmission of IP packets over serial lines.

Q

Acronym for Quality of Service, which can be either a network-oriented measure--such as bit-error rate--or a user-oriented measure, relating to the perceived quality received by the end user for audio, video, or multimedia applications.

R

Acronym for Real-time Transport Protocol, which provides end-to-end network transport functions suitable for applications transmitting real-time data, such as audio, video, or simulation data.

S

Acronym for Serial Line Internet Protocol, which is currently a de facto standard, commonly used for point-to-point serial connections running TCP/IP. It is not an Internet standard, See PPP.

T

A digital transmission link with a capacity of 1.544 Mbps. The lines are widely used to connect networks across remote distances. T-1 uses two pairs of normal twisted wires, as is common in private homes. T-1 supports 24 voice conversations, each one digitized at 64 Kbps.

T-1 is a standard for digital transmission in the U.S., Canada, Hong Kong, and Japan. In Europe, the equivalent is an E-1 which can handle 30 voice channels.

Acronym for Transmission Control Protocol, a protocol for verifying correct data delivery between two systems. TCP detects errors, or lost data, and triggers retransmission until the destination receives the correct data. TCP generally uses the IP protocol to transmit the information.

Acronym for Transmission Control Protocol/Internet Protocol, a networking protocol that provides communication across interconnected networks, between computers with diverse hardware architectures, and between various operating systems.

U

Acronym for User Datagram Protocol, a packet-based, wireless protocol. Unlike connection-based protocols (such as TCP), there is no distinction between the originator of the request and the response to it.

W

Acronym for Wide Area Network, a communications network that covers a wide geographic area, such as a state or a country.