band from 10BaseFP. Standard for running Ethernet LAN over passive opti- 300Hz to 3400Hz.) cal fibre. Voice Frequency Carrier Telegraph. 10BaseT. Standard for running Ethernet LAN over twisted copper Very High Frequency. (Radio frequency in the range wire. of about 30MHz and 300MHz.) Abbreviated dialling. A feature available in some telephone swit- VHSIC Very High Speed Integrated Circuit. ches which enable the user to establish a connection by entering Very Low Frequency. (Radio frequency in the range fewer digits than would otherwise be required. of about 3kHz to 30kHz.) Access charge. The same as interconnection charge. Visitor Location Register. (Database associated with Access line. Usually refers to the line which provides a permanent a MCS in a mobile radio system, containing infor- connection between a subscriber and his local exchange. mation of its current users.) Accounting rate. Private bilateral agreement between carriers, Very Large Scale Integration. (A complex integrated which is used to determine the allocation of revenues from circuit.) international calls. Voice Messaging System. Acoustic coupler. Device that connects to a telephone handset and Via Net Loss. (The method use to assign minimum converts sounds into electrical data for transmission down a loss in telephone lines in order to control echo and telephone line. singing.) Adaptive equalisation. Technique, commonly used with modems, Voice Of America. for compensating for differences in the attenuation charac- Virtual Private Network. (Part of a network operated teristics of telephone lines. by a public telephone operator, which is used as a Adaptive predictive coding. A coding technique which predicts private network.) the present value of the input sample, based on the previous Vector Quantisation. (Encoding method.) cycle. Variable Quantising Level. (Speech encoding Adaptive quantisation. Quantisation in which the step sizes are method for transmission of speech at 32kbit/s.) varied so as to match the changes in the input signal. Vertic