Technical information

Integrators’ Reference Manual for ViewStation EX, ViewStation FX, and VS4000
4 www.polycom.com
CIF Common Intermediate Format, also called FCIF.
A video format providing resolution of 352 x 288
pixels. See also QCIF, 4CIF, 16CIF.
Client A networked PC or terminal that shares services
with other PCs. These services are provided by a
server.
Conference
Call
Any call that establishes all-way communication
between three or more endpoints.
CPE Customer Premises Equipment.
CRC Cyclic Redundancy Check.
CSU Channel Service Unit.
D channel Data channel. The D channel carries the call
protocol signals.
Data
Conferencing
Enables people in different locations to work on
the same document via networked computers.
Also called collaborative computing.
DB-25 The standard 25-pin connector used for RS-232
serial data communications.
DCE Data Communications Equipment.
DHCP Dynamic Host Configuration Protocol. DHCP
servers permit multiple devices to share a group
of IP addresses, assigning IP addresses to specific
devices as needed.
DID Direct Inward Dial.
Digital Line A telephone line that carries audio encoded as a
digital signal, which must be decoded to analog at
the destination. ISDN uses digital signaling.
Downstream Closer to the endpoint. For example, the
peripheral side of a network interface module is
downstream of the network side.
DSL Digital Subscriber Line. Uses existing copper
telephone lines and connects to the telephone
company’s central office. See also ADSL.