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ISDN-TRK (DS1 ISDN Trunk)
Issue 4 May 2002 10-981 555-233-123
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Maintenance/Near-end (MTC/NE)
The trunk (B-channel) is in this state if the signaling link (PI-LINK) is busied
out by system technician. The trunk (B-channel) is also temporarily in this
state if system technician has issued a test trunk trunk_group/trunk_
member long command. This command will execute the ISDN-PRI test
call. This test will change the state of the trunk member to MTC/NE for the
duration of the test unless a call request comes in from the far-end. In that
case, the test would abort. Note that transitions into MTC/NE do not drop
stable calls. Therefore, a system technician- demanded busyout link
lnk-no command will not drop stable trunk calls. In this state, the
B-channel is not usable for new outgoing calls, but is available for incoming
calls and outgoing test calls.
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Pending States
If the near-end is expecting a timed response from the far-end for a request
to change the service state of a trunk, then the state of the trunk reflects a
Pending State.
— Pending-in-service (PINS)
The near-end has sent a B-channel maintenance message to the
far-end, requesting that the B-channel service state be transitioned
to in-service. The far-end has a certain amount of time to respond to
the message. The service state will be PINS until either a response
is received or the timer expires.
— Pending-maintenance (PMTC)
This state is supported only by systems using country protocol 1
(including US). The near-end has sent a B-channel maintenance
message to the far-end, requesting that the B-channel service state
be transitioned to maintenance. The far-end has a certain amount of
time to respond to the message. The service state will be PMTC
until either a response is received or the timer expires.
— Call Activity States
In addition to the service and pending state, the state of a B-channel
also reflects its call activity. If a call is connected over the B-channel,
then the state of the trunk will reflect the “active” call state, for
example, “in-service/active.” If there is no call on the B-channel,
then the trunk will reflect the “idle” call state, for example,
“OOS/FE-idle.”
The following diagram of the DS1 ISDN Trunk service states shows the
common progression from one service state to another and the event that
caused the change of state.