Service verification 10-9
Digital Switching Systems DMS-250 ISDN Reference Manual MWC14 (CSP14)
Table 10-1
PRI trunk states
(continued)
PRI trunk state Explanation
Call processing deload
(CPD)
The circuit is currently carrying traffic; however, another entity has
requested to be informed when the circuit is released. Usually,
maintenance on the circuit is pending.
D-channel fail (DFL) The D-channel associated with this B-channel is not in service and
no messaging can take place.
D-channel manual busy
(DMB)
The state an ISDN PRI trunk member has when the D-channel
handler (DCH) associated with the D-channel is out of service.
Every member in the trunk group that is not INB and is associated
with the out-of-service DCH sustains the state D-channel manual
busy (DMB) until the DCH is returned to service.
Idle (IDL) The trunk member is in service and idle.
Installation busy (INB) The circuit is installed but has not yet been placed in service.
Lockout (LO) The D-channel associated with the facility is in service. However,
CCS7 layer 3 cannot communicate with the far end because there
is no synchronization over CCS7 layer 2; there is synchronization
but no logical link is established; and CCS7 layer 3 is not
responding to a restart or release.
Manual busy (MB) The circuit is removed from service by a maintenance person.
Peripheral manual busy
(PMB)
The circuit is not available because the associated peripheral (the
PRI DTCI) is out of service.
Remote make busy
(RMB)
A circuit has the state RMB when the far end of the B-channel is
removed from service. As a result, call setup fails.
System busy (SB) The circuit is removed from service by system maintenance;
system maintenance performs periodic tests.
—end—
Restoring service to the PRI trunk on the DMS-250 switch
Table 10-2 lists the various actions to be taken based on trunk states shown
at the DMS-250 switch MAP terminal.
If the problem is due to the DCH—that is, B-channel states in D-channel
manual busy (DMB), D-channel fail (DFL), and lockout (LO)—refer to
Table 10-4 for troubleshooting information.
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