Canon FAX-L260i Service Manual page 171

Example) G4/G3 Fallback function and operation procedure
• In the case where the FAX-L260i makes on outgoing G4 call to a G3 machine
a) After the FAX-L260i sends the SETUP message which includes the Bearer Capability information
element "unrestricted digital." notification of a DISC message containing Cause number "88" is made
from the network, and a D-channel connection error occurs. Cause number "88" means "Incompatible
Destination." and the FAX-L260i displays the service error code "##1088." The "cause number" is set to
the clearing message first notified by the network (DISC message, REL message, or RELCOMP message).
FAX-L260i
Figure 3-18 G4 -> G3 Fallback Procedure (1)
b) Next, the 4 digits "1088" of the service error code "##1088" are registered in service data #4B 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.
FAX-L260i
Figure 3-19 G4 -> G3 Fallback Procedure (2)
FAX-L260i Chapter 3: Maintenance & Service
SETUP (BC: "Unrestricted digital")
CALL PROC
DISC (Cause number: "88")
REL
REL COMP
D-channel error
Display the service error code "##1088"
SETUP (BC: Unrestricted digital)
CALL PROC
DISC (Cause number: "88")
REL
REL COMP
G4/G3 Fallback
procedure
SETUP (BC: 3.1kHz audio)
CALL PROC
CONN
CONN ACK
3-75
ISDN
G3 machine
ISDN
G3 machine
BC: Bearer Capability