Ncauui; Ncauui (Non Call Associated User-To-User Information) - Nortel DMS-250 Reference Manual

NCAUUI

NCAUUI (Non Call Associated User-to-User Information)

NCAUUI provides a service that allows PRI users located on the same
switch to communicate by means of user-to-user signaling without setting up
bearer channels at network access and egress points. In particular, the
DMS-250 switch supports only the NTMCIPRI and N449PRI variant
originations and terminations. The switch does not use bearer channels
when establishing an NCA–TSC.
The system offers NCAUUI on a subscription basis at the switch level.
After receiving a Q.931 SETUP message with a NCAUUI request, the
DMS-250 switch verifies the subscription of the originating user before
further processing the request.
After verifying the originating user is subscribed to NCAUUI, the DMS-250
sends an ADF DAL Request message to the DAP based on VNET or
FLEXSAC call processing. The DAP validates the ADF DAL request for
NCAUUI. After the DAP validates the ADF DAL request, the DAP returns
an ADF Routing Response or an ADF Suppcode Response containing the
subsequent address, terminating switch ID (TSID) and terminating trunk
group (TTG) to the DMS-250. After receiving the ADF Routing Response,
call processing routes the Q.931 SETUP message indicating NCAUUI to the
terminating PRI user based on the TTG. If the DAP fails the ADF DAL
request, the DAP returns an ADF Failure Response to reject the ADF DAL
request.
When the terminating user receives the Q.931 SETUP message, the
terminating user can acknowledge the NCAUUI request with a Q.931
CONNect message.
Once the switch establishes an NCA-TSC, either user may send User
Information messages. The switch makes no attempt to interpret the contents
of the User Information messages.
If the length of the User Information exceeds the maximum allowable length
(251 bytes), the switch discards the message. The switch sends a Status
message to the sender of the User information message with a cause value of
Digital Switching Systems DMS-250 ISDN Reference Manual MWC14 (CSP14)
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