Webcam - A video camera, usually attached directly to a computer, whose current or latest image is requestable from a Web site. 

Webcasting - (push technology) is the prearranged updating of news, weather, or other selected information on a computer user's desktop interface through periodic and generally unobtrusive transmission over the World Wide Web (including the use of the Web protocol on intranets). 

Wideband - A medium-capacity communications circuit/path. It usually implies a speed from 64Kbps to 1.544Mbps.

Wink start signaling - Method of supervisory signaling. CPE signals offhook condition by sending a momentary pulse to the CO. Contrast ground start and loop start.

Wire center - Any point in a telecommunications network where the network's wiring is exposed to provide access.

XDSL - An umbrella term used to describe an emerging family of "digital subscriber line" technologies. These technologies enable existing twisted pair telco lines to become the transport mechanism for multimedia and high-speed data transmission technologies without impacting the Public Switched Telephone Network or central office switch.

XMODEM - An error -correcting file transfer, data transmission protocol used to transmit files between PCs. The XMODEM protocol sends information in 128 byte blocks of data. Some sums (check sums) are done on each block and the result is sent along with the block. If the result does not check out at the other end, the computer at the other end sends a request ( a NAK - negative acknowledgment ) to retransmit that block once again. If the block checks out, the computer sends ACK ( an acknowledgment ). In this way, relatively error-free transmission can be accomplished.

X.21 - Same as RS-449 with in-band dialing capability.