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GLOSSARY

V.xx
VIDEOCONFERENCE
VC - VIRTUAL CIRCUIT
VIRTUAL HOSTING
VPN - VIRTUAL PRIVATE NETWORK
VIRUS
VIRUS HOAX
VoIP - VOICE over INTERNET PROTOCOL
VOICE-ENABLED E-MAIL

V.xxThe V Series Recommendations from the ITU-TS are summarized in the table below. They include the most commonly used modem standards and other telephone network standards. Prior to the ITU-T standards, the American Telephone and Telegraph Company and the Bell System offered its own standards (Bell 103 and Bell 212A) at very low transfer rates. Another set of standards, the Microcom Networking Protocol, or MNP Class 1 through Class 10 (there is no Class 8), has gained some currency, but the development of an international set of standards means these will most likely prevail and continue to be extended. (Some modems offer both MNP and ITU-T standards.) In general, when modems handshake, they agree on the highest standard transfer rate that both can achieve (bis refers to a "second version." terbo refers to a "third version.").

Standard Meaning
V.22 Provides 1200 bits per second at 600 baud (state changes per second)

V.22bis The first true world standard, it allows 2400 bits per second at 600 baud V.32 Provides 4800 and 9600 bits per second at 2400 baud

V.32bis Provides 14,400 bits per second or fallback to 12,000, 9600, 7200, and 4800 bits per second

V.32terbo Provides 19,200 bits per second or fallback to 12,000, 9600, 7200, and 4800 bits per second; can operate at higher data rates with compression; was not a CCITT/ITU standard

V.34 Provides 28,800 bits per second or fallback to 24,000 and 19,200 bits per second and backwards compatility with V.32 and V.32bis

V.34bis Provides up to 33,600 bits per second or fallback to 31,200 or V.34 transfer rates

V.35 The trunk interface between a network access device and a packet network at data rates greater than 19.2 Kbps. V.35 may use the bandwidths of several telephone circuits as a group. There are V.35 Gender Changers and Adapters.

V.42 Same transfer rate as V.32, V.32bis, and other standards but with better error correction and therefore more reliable

V.90 Provides up to 56,000 bits per second downstream (but in practice somewhat less). Derived from the x2 technology of 3Com (US Robotics) and Rockwell's K56flex technology.

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VIDEOCONFERENCE is a live connection between people in separate locations for the purpose of communication, usually involving audio and often text as well as video. At its simplest, videoconferencing provides transmission of static images and text between two locations. At its most sophisticated, it provides transmission of full-motion video images and high-quality audio between multiple locations.

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VC, A Virtual Circuit is a circuit or path between points in a network that appears to be a discrete, physical path but is actually a managed pool of circuit resources from which specific circuits are allocated as needed to meet traffic requirements.
A permanent virtual circuit (PVC) is a virtual circuit that is permanently available to the user just as though it were a dedicated or leased line continuously reserved for that user. A switched virtual circuit (SVC) is a virtual circuit in which a connection session is set up for a user only for the duration of a connection. PVCs are an important feature of frame relay networks and SVCs are proposed for later inclusion.

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VIRTUAL HOSTING is the provision of Web server hosting services so that a company (or individual) doesn't have to purchase and maintain its own Web server and connections to the Internet. A virtual hosting provider is sometimes called a Web or Internet "space provider". Some companies providing this service simply call it "hosting". Typically, virtual hosting provides a customer who wants a Web site with: domain name registration assistance, multiple domain names that map to the registered domain name, an allocation of file storage and directory setup for the Web site files (HTML and graphic image files), e-mail addresses, and, optionally, Web site creation services. The virtual hosting user (the Web site owner) needs only to have a File Transfer Protocol (FTP) program for exchanging files with the virtual host.

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VPN, Virtual Private Network is a private data network that makes use of the public telecommunication infrastructure, maintaining privacy through the use of a tunneling protocol and security procedures. A virtual private network can be contrasted with a system of owned or leased lines that can only be used by one company. The idea of the VPN is to give the company the same capabilities at much lower cost by using the shared public infrastructure rather than a private one. Phone companies have provided secure shared resources for voice messages. A virtual private network makes it possible to have the same secure sharing of public resources for data. Companies today are looking at using a private virtual network for both extranets and wide-area intranets.

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VIRUS is a piece of programming code usually disguised as something else that causes some unexpected and usually undesirable event. A virus is often designed so that it is automatically spread to other computer users. Viruses can be transmitted as attachments to an e-mail note, as downloads, or be present on a diskette or CD. The source of the e-mail note, downloaded file, or diskette you've received is often unaware of the virus.

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VIRUS HOAX is a false warning about a computer virus Typically, the warning arrives in an e-mail note or is distributed through a note in a company's internal network. These notes are usually forwarded using distribution lists and they will typically suggest that the recipient forward the note to other distribution lists.
If you get a message about a new virus, you can check it out by going to one of the leading Web sites that keep up with viruses and virus hoaxes. If someone sends you a note about a virus that you learn is a virus hoax, reply to the sender that the virus warning is a hoax.

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VoIP (Voice over IP - that is, voice delivered using the Internet Protocol) is a term used in IP telephony for a set of facilities for managing the delivery of voice information using the Internet Protocol (IP). In general, this means sending voice information in digital form in discrete packets rather than in the traditional circuit-committed protocols of the public switched telephone network (PSTN). A major advantage of VoIP and Internet telephony is that it avoids the tolls charged by ordinary telephone service.
VoIP, now used somewhat generally, derives from the VoIP Forum, an effort by major equipment providers, including Cisco, VocalTec, 3Com, and Netspeak to promote the use of ITU-T H.323, the standard for sending voice (audio) and video using IP on the public Internet and within an intranet. The Forum also promotes the user of directory service standards so that users can locate other users and the use of touch-tone signals for automatic call distribution and voice mail.
In addition to IP, VoIP uses the real-time protocol (RTP) to help ensure that packets get delivered in a timely way. Using public networks, it is currently difficult to guarantee Quality of Service (QoS). Better service is possible with private networks managed by an enterprise or by an Internet telephony service provider (ITSP).

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VOICE-ENABLED E-MAIL (sometimes referred to as voice-activated e-mail) uses voice recognition and speech synthesis technologies to enable users to access their e-mail from any telephone. In general, the various products available work similarly: The subscriber dials a phone number to access a voice portal, then, to collect their e-mail messages, they press a couple of keys and, perhaps, say a phrase like "Get my e-mail." Speech synthesis software converts e-mail text to a voice message, which is played back over the phone. The user may navigate through options (such as skipping messages, or hearing a list of senders, for example) through voice commands or key selections. Users dictate their replies, which are delivered to the recipients as voice messages.

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