Telecom Dictionary

A - B - C - D - E - F - G - H - I - J - K - L - M - N - O - P - Q - R - S - T - U - V - W - X - Y - Z

VAD 
value-added distributor

VAN 
value-added network

VAR 
value-added reseller

VBR 
variable bit rate

VCI 
virtual circuit identifier

VCS 
virtual circuit switch

Very Small Aperture Terminal (VSAT)
VSATs are earth terminals using small antennas (1.5 6 feet in diameter). This technology typically 
operates in the Ku band (11/14 GHz), and Ka band (20/30 GHz).

Video Conferencing
Video conferencing is the real-time, usually two-way transmission of voice and images between 
two or more locations. Today, both voice and video analog signals are digitized by video codices 
before transmission which can involve wide bandwidths. To conserve bandwidth, some systems 
employ "freeze frame," where a television screen is only "repainted" every few seconds. Codecs 
for higher quality full motion video attempt to minimize bandwidth requirements by taking 
advantage of intervals with relatively little motion (which require smaller bandwidths), and by 
trading off smooth motion tracking and picture resolution.

Virtual Private Networks (VPN)
VPNs are services using public network facilities augmented by network control point and service 
management system facilities wherein traffic is routed through the public network under 
computer control in a manner that makes VPN service indistinguishable from dedicated facilities 
based private networks. Customers can define, change and control network resources with the 
same or more flexibility as afforded by facilities based private networks.

VPI 
virtual path identifier

VPN 
virtual private network

VRU 
voice response unit

VSAT 
very small aperture terminal