VDSL
Very High Data Rate Digital Subscriber Line 
See ADSL

VF
Voice Frequency

VHDCI
Very High Density Cable Interconnect 
The 68-pin Very High Density Cable Interconnect connector introduced in the SPI-3 document of SCSI-3. The VHDCI connector is a very small connector that allows placement of four wide SCSI connectors on the back of a single PC card slot. Physically, it looks like a miniature Centronics type connector. It uses the regular 68-contact pin assignment.

VIC
Voice Interface Card

VLAN
Virtual Lan Area Network
A logical group of user end stations, servers, and other network devices that appear to be on the same LAN, regardless of their physical location

¥ The switches can be parametered so a specific workstation can reach any other specific workstation(s) on the LAN.
¥ The switches can be accessed and controlled directly from a console port or via the LAN using IP.
¥ The LAN Administrator can use the MAC addresses or the IP addresses to interconnect the workstations.

¥ One main advantage of this kind of LAN configuration is in the naming convention. Two workstations can use the same
name although they are physically attached on the same LAN, for test purposes for example. 
For security reason. All the workstations can be grouped by activities such as the workstations used for the Human Resources.
A resource can be limited to a group, as the access to Internet.

VNC
Virtual Network Computing ¨ is a shareware under the GNU public license. 
VNC has been developed by AT&T¨. This software enables for a remote computer.

VOFR
Voice Over Frame Relay 
FRF.11 
Comment :
64 KB 
á equivalent to 1 PVC link between two PBX 
á Frad to other Frad is used in SVC
á Jitter is less than 20 ms

Voice Compression
Process by which the high statistical correlation between consecutive voice samples is used to create a variable quantizing scale. ADPCM can encode analog voice samples into high - toll - quality digital signals.
á Used to optimize the cost
á The difference of amplitude is analyzed and compared to the former sample
á Silence are detected.
á ITU-T Norm from G.720 to G.730 

VOIP
Voice Over IP 
VOIP needs the QoS - Quality of service.
¥ In this example, based on Cisco hardware, the Call Manager behaves as a PBX. It can be placed anywhere on the WAN.
¥ 11 KB is the minimum required for a phone conversation.
¥ Both Analog phones or IP-phones can be used. 
¥ The Cisco Router can be plugged directly on a PBX or on an ISDN or Frame Relay or ADSL line.

The Call Manager configures and recognizes each IP-Phone on the LAN/WAN.
Each IP Phones are DNS. They can be plugged-unplugged anywhere on the LAN/WAN.
The Call Manager allows the connections between the phones. Once the conversation is established, the phones are connected directly,
the Call Manager keeps a track on the connection but the conversation data flow does not go through the Call Manager anymore.
Once the conversation is over, the Call Manager releases the phones.

The Foreign Exchange Station " interface. This interface is an RJ-11 connector that allows connection for basic telephone equipment, key sets PBXs, and supplies ring, voltage, and dial tone.

The FXO interface is an RJ-11 connector that allows a connection to be directed at the PSTN's central office (or to a standard PBX interface, if the local telecommunications authority permits). This interface is of value for off-premise extension applications.

E&M is a trunking arrangement generally used for two-way switch-to-switch or switch-to-network connections.

VP
Virtual Path 
A concept used to describe unidirectional transport of ATM cells belonging to virtual channels that are associated by a common identifier value.

VPC
Virtual Path Connection - ATM

VPCI
Virtual Path Connection Identifier - ATM

VPI
Virtual Path Identifier 
Identifier contained in the ATM cell header to designate the virtual path on the physical ATM link.

VPN
VPN is a secure private communication path(s) through one or more data networks that is dedicated between two points. VPN connections allow data to safely and privately pass over public networks (such as the Internet). The data traveling between two points is encrypted for privacy.

VSAT
Very Small Aperture - Satellite - Terminal

VTOA
Voice and Telephony Over ATM