Glossary

V

VBR
Variable bit rate

VC
Virtual circuit

VCAT
Virtual concatenation: inverse multiplexing mechanism used to split Sonet/SDH bandwidth into logical groups that can be combined into an aggregate link to achieve a commensurate increase in available bandwidth.

VDSL
Very high bit-rate digital subscriber line (also seen as VHDSL)

Virtual co-location
Where a CLEC has telecoms equipment installed, configured and maintained by an ILEC, within the ILEC’s central office.

VLAN
Virtual private local area network

VNO
Virtual network operator 

VoB
Voice over broadband

VoD
Video on demand

VoIP
Voice over internet protocol: voice traffic partly or totally routed via a packet-switched network. Pure VoIP would, according to the same definition, be voice traffic transmitted entirely via a packet-switched network and would hence not have any circuit-switched elements at all, paving the way for entirely new business models within the telecoms carrier community.

Voice Peering
Voice Peering: functions as a private voice internet that allows participants to establish peer-to-peer connections over a distributed Ethernet network. By establishing network connections with other VoIP providers, VP participants are able to route their network traffic around the PSTN. VP providers such as those who are members of the VPF ASP market areable to buy and sell services transparently with each other. Features that a VPF service provider may offer include caller ID, local number portability (LNP) and Signalling System 7 (SS7). It is claimed that VPF also allows enterprises and carriers to manage and access multiple services with a single VPF Ethernet connection without the need to provision disparate dedicated TDM connections.

VPLS
Virtual private LAN service: Supports connection of multiple subscriber sites and emulates a single bridged domain over a managed IP/MPLS network – whereby all services appear to be on the same LAN, regardless of location.

VPN
Virtual private network