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10/5/2009
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Vault (USA - also controlled environment vault)
A US term for what is known in the UK as a manhole - an underground structure used for housing cable joints and other external plant such as repeater-cases. It is usually distinguished from a surface jointing chamber (or handhole) by its size and access arrangements. A vault will usually be accessed via a cast-iron manhole cover in a pavement (sidewalk) or carriageway (road surface). Lifting the cover will reveal an access chimney, frequently with steps in the wall, leading to a large chamber in which a person can sit, or even stand, to work. Sometimes the space can be as big as a room but typical dimensions would be 2 metres x 3 metres X 2 metres high. As with all external plant proper safety procedures are of paramount importance. Apart from guarding the surface access to pedestrians and traffic, testing for gases before entry is of critical importance as there is a high potential danger of suffocation or of explosion due to the use of electrically operated equipment for lighting, jointing copper pairs, splicing optical fibres etc.
A controlled environment vault is an underground chamber intended to house electronic equipment, most notably for digital-loop carrier equipment in the USA. It is usually delivered to site as a pre-cast unit with power capability, some racks and pre-wiring in place. Typical sizes are 2 metres X 5 metres or 8 metres X 2.5 metres high.
A name for the suppliers of equipment to the telecom operators. See also procurement.
Video codec
Video conferencing
Video-on-demand
Video over IP.
A logical closed user group implemented over public network facilities for switched voice, switched data or both. See also private network. A voice realisation would be capable of providing a private numbering plan, have the ability to charge for calls on the basis of duration of usage. Users are usually located at more than one organisational site served by more than one public telephone exchange. Very often they will provide advanced features similar to PBXs, advanced billing and simplified network and communications management for the users. See also IP virtual private networks, BTTJ, Vol 18, No 3.
Similar to a service provider but without any significant owned OSS, including CRM, so that most of the activities associated with customer and service management, billing and business management systems are outsourced to the wholesaler.
A virus is a programme that causes an undesirable and unpredictable event. It is usually disguised as something else and capable of replicating itself and automatically spreading to other computers. Viruses can be transmitted within e-mails or files or even through some web-pages. Some viruses take effect immediately whilst others lie dormant until circumstances cause their code to be executed by the computer. Viruses can vary in seriousness from the production of a simple message to deleting all data from a hard disk.
The transmission of the human voice lies at the heart of telecommunications, even in a world where data traffic has long since surpassed voice traffic in terms of transmitted bits and the march of machine-to-machine (M2M) traffic continues to rise. The voice is primarily used for speech which has a number of facets dealt with here.
Voice over data.
The provision of voice communication over a network using the Internet Protocol (IP).
VoIP - BTTJ, Vol 19, No 2.
VoIP gateways and the Megaco architecture, BTTJ, Vol 19, No 2.
Most services in telecommunications are based on fixed-price subscription (flat rate) or time-based billing. An example of the former is leased-line private circuits. The most common form of the latter is the timed telephone call, from both both fixed and mobile operators, with the price being dependent on the amount of time the telephone is in use for the call. As the use of the Internet and related technologies increased most customers wanted their access to be "always on" - that is always available to use when required. In radio systems this also means that expensive radio resources are only allocated when data is being transferred. This can be met by flat-rate services provided assumptions about usage are made and that no single user departs significantly from the assumptions. Unfortunately, fixed-rate is sometimes regarded a 'free' and as with anything free at the point of sale the demand can be infinite. Many people consider that because they have a 500 kbit/s broadband connection they can pass 500 kbit over it for every second of every day. In the early days of the Internet many service providers played a cat and mouse game with certain customers who they regarded as "abusing" the service by over use - instead of just browsing the web they were running servers from home (usually classed as business even if for a hobby) or constantly streaming video material. Similarly mobile operators had no basis on which to make assumptions of usage of early GPRS and 3G data services. The alternative is to bill for the number of bits transferred (volume-based) and early GPRS services took this approach. Whilst installing bit counters is possible there are other issues that arise, notably that people can be sent data that they did not request or want. Evolution to volume-based billing is still under way.
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