228 IBM ISDN PC Card:User’s Guide
interface is similar to an E1 line. The total data rate is 2.048 Mbit/s. However,
the PRI provides 30 ISDN B channels and one D channel, all operating at 64
kbit/s. PRIs can be used in large RAS environments.
•S0 interface - Another name for the BRI interface in Europe, where the
telephone company generally provides the NT device. For BRIs in point-to-
multipoint configuration, the S0 interface is a four-wire data bus.
•S2M interface - Another name for the PRI in Europe.
•S/T interface - The European reference point for connecting ISDN terminal
equipment to the ISDN network. This interface is provided by the NT-1,
which in Europe is furnished by the telephone company.
•SLIP - Serial Line Internet Protocol. A TCP/IP protocol used for
communication between two machines that have been previously configured
for communication with each other. Your Internet service provider can
provide you with an SLIP connection, for example, so the provider’s server
can respond to your requests, pass them on to the Internet, and forward your
responses from the Internet back to you. Your dial-up connection server is
typically on a slower serial line, rather than on the parallel or multiplex lines,
such as those of a provider’s network. SLIP only works with staticIP
addresses and is considered obsolete. SLIP works on OSI layer 2.
•SPID - The Service Profile Identifier (SPID) is a number assigned by the
telephone company to a terminal on an ISDB B channel. A SPID tells
equipment at the phone company’s central office about the capabilities of each
terminal (computer, phone etc.) on the B channels. A basic-rate home or
business user can 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 information. 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. Beginning 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
corporate installation procedures. SPIDs are used only in the United States of
America and Canada.
•Supplementary Service - Additional ISDN capabilities that are available only
in Euro ISDN. Some of them are standard convenience features, others are
only are available upon request. Supplementary Services include Calling Line
Identification (CLI), Call Forwarding (CF), Closed User Group (CUG), etc.
Your telephone company can provide more information on Supplementary
Services.
•T carrier system - The T carrier system, introduced by the Bell System in the
U.S. in the 1960s, was the first successful system that supported digitized
voice transmission. The original transmission rate (1,544 Mbit/s) of the T1 line
is in widespread use today in enterprise connections to the Internet. A higher
multiplex level, the T-3 line, providing 44,736 Mbit/s, is also commonly used
by Internet service providers. Another commonly installed service is
fractional T1, which is the rental of some portion of the 24 channels in a T1
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