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226 IBM ISDN PC Card:User’s Guide
“Memorandum of Understanding” which led to the implementation of Euro
ISDN in 1993. Euro ISDN is documented in the ETSI Net-3 standard.
• Fax standards - There are two important fax standards for ISDN:
— G3 (Group 3, ITU standard T.4) which comes from the analog telephony
world and allows a maximum resolution of 200 dpi by 200 dpi. Transfer
speeds usually are 2,400 bps, 4,800 bps, 7,200 bps, 9,600 bps, and 14.4 kbps.
The IBM International ISDN PC Card supports the fax G3 standard.
— G4 (Group 4, ITU standard T.6) is a digital fax standard which is available
only in ISDN. It allows a maximum resolution of 400 dpi by 400 dpi.
Transfer speeds are 2,400 bps, 4,800 bps, 9,600 bps, 48 kbps, and 64 kbps.
However there are hardly any G4 fax devices on the market, and they are
prohibitively expensive. G4 stands for Group 4 (ITU standard T.6).
• Fossil - Fido Opus Seadog Standard Interface Layer. This is a modem
emulation standard developed for analog BBS communications. A FOSSIL
device driver supports most of the AT commands set used by analog modems.
• Hot insertion/removal - Denotes the installation or removal of a peripheral
device when the system is powered on and running.
• ISDN voltage - The ISDN network voltage at the subscriber interface, where
the ISDN terminal equipment is connected, is 40 VDC.
• ITU - International Telecommunication Union. A United Nations body which
develops recommendations for international telecommunication standards.
• kbps, kbit/s - megabits per seconds One Mbit/s is 1,000,000 bits per second,
or 125,000 bytes per second, or roughly 122 kilobytes per second.
• Mbps, Mbit/s - megabits per seconds One Mbit/s is 1,000,000 bits per second,
or 125,000 bytes per second, or roughly 122 kilobytes per second.
• MSN - Multiple Subscriber Number. A feature that is available only in Euro
ISDN. SOme telephone companies assign multiple numbers to each ISDN
subscriber line ordered. These MSNs are usually (but not necessarily) in
sequence starting with ISDN line’s primary number. Each MSN is an
independent telephone number. Each ISDN terminal device connected to the
line can be assigned one of the line’s MSNs to permit internal call routing. Ask
your ISDN service provider if your line will be equipped with MSNs and, if
so, how many.
Note: MSNs can be assigned to terminal equipment without regard to
sepcific ISDN services.
• Multilink - A multilink connection is one that uses two or more B channels as
a single communication link. The two B channels of a BRI can be bundled to
yield a data rate of 2x64 kbit/s. Multilink connections generally result in
higher connection charges.
• NT-1 - Network Terminator 1. This is the endpoint of the ISDN network at the
customer premises. The term also denotes a device which is connected to the
U interface and provides the S/T interface to subscriber equipment.
• OSI reference model - The Open Systems Interconnection model is a standard
description or "reference model" of data transmission between any two points
in a communication network. Its purpose is to guide product developers and
maximize interoperability among different products. The reference model
ISDNmst.fm Page 226 Wednesday, January 15, 2003 9:22 AM