Trend AuroraPlus User Guide
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Protocol Discriminator Identifies the protocol.
Call Reference Value Identifies the call with which a
message is to be associated.
Message Type Describes the intention of the
message: CONNECT, SETUP,
etc.
Information Elements A number of these may be
included. The number and
content depend on the message
type.
Protocols
A protocol is an agreed set of rules for carrying out a
particular function such as the exchange of information.
ETSI
The ITU Q921 and Q931 recommendations are the basis of
what is commonly known as the ETSI protocol. Q931
defines the call control messages and Q921 defines the
frames that carry the messages. ETSI is the standard ISDN
protocol used within Europe.
VN
VN is the national ISDN protocol for France and it is also
used in private networks utilising equipment of French
origin. VN is similar in many respects to the ETSI protocol,
the main differences being the construction of layer 3
messages and information elements, new message types and
different teleservices.
Chap01.P65 30/04/01, 16:2718
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