IBM International ISDN User Manual page 206

Appendix C: A Brief ISDN Glossary
Glossary
SLIP
SPID
206 ISDN PC Card – 17 Appendix C: A Brief ISDN Glossary
Serial Line Internet Protocol. A TCP/IP protocol
used for communication between two machines
that have been previously configured for commu-
nication with each other. Your Internet server pro-
vider may provide you with a SLIP connection for
example, so that the provider's server can re-
spond to your requests, pass them on to the Inter-
net, and forward your responses from the Internet
back to you. Your dial-up connection to the server
is typically on a slower serial line, rather than on
the parallel or multiplex lines such those of a pro-
vider's network. SLIP only works with static IP ad-
dresses and is considered obsolete. SLIP works
on OSI Layer 2.
The Service Profile Identifier (SPID) is a number
assigned by the phone company to a terminal on
an ISDN B channel. A SPID tells equipment at the
phone company's central office about the capa-
bilities of each terminal (computer, phone etc.) on
the B channels. A basic-rate home or business us-
er may divide service on the two B channels using
one for normal telephone service and the other
for data. The SPID tells the phone company
whether the terminal accepts voice or data infor-
mation. Technically, the SPID is a numeric string
from 3 to 20 digits in length. One or more SPIDs
are assigned when you order the ISDN basic-rate
interface (BRI) from the phone company. Begin-
ning in 1998, most phone companies began to
use a generic SPID format. In this format, the SPID
is a 14-digit number that includes your 10-digit
telephone number (which in turn includes the 3-
digit Numbering Plan Area [NPA] or area code), a
2-digit Sharing Terminal Identifier, and a 2-digit
Terminal Identifier (TID). The generic SPID format
makes it easier to tell users what to specify when
installing ISDN equipment, and simplifies corpo-
rate installation procedures. SPIDs are used only
in the USA and Canada.