Canon FAX L1000 Service Manual page 521

3.6.6 ISDN Protocol Messages
Main messages which are used in the communication protocols of Layer 2 - Layer 3 of the
control channel's D-channel and Layer 2 - Layer 6 of the information channel's B-channel are
listed.
a) D-channel messages
Layer 2
Message
SABME
Set Asynchronous Balanced
Mode Extended
UA
Unnumbered Acknowledge
DISC
Disconnect
Layer 3 (Continue)
Message
SETUP
Request for call settings
SETUP ACK SETUP Acknowledge
CALL PROC Call Proceeding
CONN Connect
CONN ACK Connect Acknowledge
ALERT Alerting
DISC Disconnect
Description
The first thing sent when layer 2 is set.
A reply message for SABME, DISC.
Sent when layer 2 is released.
Description
First sent by the calling party after setting
layer 2 when making call settings. For the
called party, it does not matter whether or
not layer 2 is connected, SETUP will be
done anyway. Then, if layer 2 has not been
connected on the called party, it will be
connected, and following that CONN, etc.
will be sent.
SETUP confirmation (request for
additional information).
This means that the calling party SETUP
has been received by ISDN. It is an option
message.
On the calling party, receives when the
other terminal has responded. On the called
party, sent for accepted SETUP when able
to respond.
On the calling party, sent for received
CONN. On the called party, ISDN sent for
the transmitted CONN.
On the calling party, receives when the
other terminal is in a call. On the called
party, sent when the user is in a call. It is an
option message.
Sent when layer 3 is disconnected.
Receives when disconnected from ISDN.
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FAX-L1000 Chapter 5: Appendix
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