Agilent Technologies Auroraduet N1726A, Руководство пользователя, Страница: 411 / 507

aurora
Duet
- User Guide
A1 - 10 422685
About Bearer Capabilities, HLCs and LLCs
ISDN terminal compatibility can be checked at the
intended destination
before a call is established. This is
achieved by including Bearer Capability, Low Layer and
High Layer Compatibility information elements in the
outgoing and incoming Call Setup messages.
Bearer Capability
The bearer capability (BC) information element is
mandatory. It tells the originating network what kind of
link bearer capability is required to route the call. The
remote terminal can then decide, based on the bearer
capability, to answer or ignore the call.
Bearer Services and Teleservices
ISDN services take two forms: Bearer Services and
Teleservices. A Bearer Service (e.g. Data 64K) provides
the basic capability for transmission of signals between
user-network interfaces. A Teleservice (e.g. Telex)
provides the complete capability for communication
between users by means of terminals, network functions
etc., according to established protocols.
Information about the Bearer Service is contained in the
bearer capability information element, and information
about the Teleservice in the Higher Layer Compatibility
information element.
The following bearer services are supported by aurora
Duet
:
• Speech
• 3.1 KHz audio
• Unrestricted Digital Information (64 kbit/s 'Data'
call)
• Unrestricted Digital Information with tones/
announcements (7 KHz audio call).
Appx1.PM6 17/06/99, 09:54 10