Bay Networks 6300 Supplement Manual page 33

Book A
Remote Annex 6300 Supplement to the Remote Annex Administrator's Guide for UNIX
For example, a business can subscribe to ISDN PRI service to connect
its local area network (LAN) to the local telephone company.
Telecommuters and mobile workers (e.g., sales staff) can continue to use
analog modem links to communicate with their company. Also, a home
computer user can use an analog modem link to call a local telephone
number for Internet access. The local telephone company processes the
call, then directs it through ISDN PRI lines to the Internet access service
provider.
Integrating Existing Analog Devices with ISDN
Users who replace their analog telephone line with ISDN BRI service do
not need to give up their analog equipment (telephone, modem, fax
machine, etc.). Using analog equipment on an IDSN line offers these
users higher speed transmission rates while preserving their investments
in analog equipment. The devices access BRI service through the use of
a device called a terminal adapter (TA).
A TA performs two tasks:
• Call set up, tear down, and management signaling conversion.
This allows analog devices to set up calls and connections
through the ISDN BRI.
• Converts the transmission of voice and data from analog to
digital. For synchronous and asynchronous data passed to it, the
TA adapts the data for transmission over the ISDN B channel.
Most TAs perform this task according to the ITU V.120
standard. The process is known as V.120 rate adaptation.
Chapter 1 Introduction to the Remote Annex 6300
A-5