Canon FAX-L1000 - Manual (Page 483)

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FAX-L1000 Chapter 5: Appendix
b) Next, the 4 digits “1088” of the service error code “##1088” are registered in service
data #4C ISDN BASIC G4/G3 Fallback , and another outgoing call is made to the G4.
In this situation, with the first outgoing call, a) D-channel cannot be connected in the
same way, but after receiving the RELCOMP message from the network, the Bearer
Capability information element included in the SETUP message is changed from
“unrestricted digital” to “3.1kHz audio” and the SETUP message is sent again.Example)
Figure 5-57 G4 / / / / / G3 Fallback Procedure (2)
G3 machine
CONN ACK
CONN
CALL PROC
SETUP (BC: Unrestricted digital)
ISDN
Dch
La
y
e
r
3
Protocol
REL
DISC (Cause number: "88")
SETUP (BC: 3.1kHz audio)
BC: Bearer Capability
REL COMP
CALL PROC
G4/G3 Fallback
procedure
FAX-L1000