V85 Desktop VoIP Phone User Guide 55
YML772 Rev1
while IP is responsible for delivering the packets from source
to destination. When TCP and IP are bundled with higher-level
applications such as HTTP, FTP, Telnet, etc., TCP/IP refers to this
whole suite of protocols.
Telnet An interactive, character-based program used to access a remote
computer. While HTTP (the web protocol) and FTP only allow you
to download files from a remote computer, Telnet allows you to log
into and use a computer from a remote location.
TFTP Trivial File Transfer Protocol. A protocol for file transfers, TFTP is
easier to use than File Transfer Protocol (FTP) but not as capable or
secure.
TTL Time To Live A field in an IP packet that limits the life span of that
packet. Originally meant as a time duration, the TTL is usually
represented instead as a maximum hop count; each router that
receives a packet decrements this field by one. When the TTL
reaches zero, the packet is discarded.
Twisted pair The ordinary copper telephone wiring long used by telephone
companies. It contains one or more wire pairs twisted together to
reduce inductance and noise. Each telephone line uses one pair. In
homes, it is most often installed with two pairs. For Ethernet LANs,
a higher grade called Category 3 (CAT 3) is used for 10BASE-T
networks, and an even higher grade called Category 5 (CAT 5) is
used for 100BASE-T networks. See also 10BASE-T, 100BASE-T,
Ethernet.
upstream The direction of data transmission from the user to the Internet.
USB Universal Serial Bus A serial interface that lets you connect devices
such as printers, scanners, etc. to your computer by simply plugging
them in. The ADSL modem is equipped with a USB interface for
connecting to a stand-alone PC.
VC Virtual Circuit A connection from your ADSL modem to your ISP.
VCI Virtual Circuit Identifier Together with the Virtual Path Identifier
(VPI), the VCI uniquely identifies a VC. Your ISP will tell you the
VCI for each VC they provide. See also VC.
VPI Virtual Path Identifier Together with the Virtual Circuit Identifier
(VCI), the VPI uniquely identifies a VC. Your ISP will tell you the
VPI for each VC they provide. See also VC.
WAN Wide Area Network Any network spread over a large geo graphical
area, such as a country or continent. With respect to the ADSL
modem, WAN refers to the Internet.
Web browser A software program that uses Hyper-Text Transfer Protocol (HTTP)
to download information from (and upload to) web sites, and
displays the information, which may consist of text, graphic images,
audio, or video, to the user. Web browsers use Hyper-Text Transfer