Definity ECS Admin for Network Connectivity.pdf - TextFiles.com

Distributed Communications System
B Private Networking
Distinctive Ringing • Distinctive Ringing
• D-channel Backup
In the event of a D-channel switchover (primary to secondary or secondary back
to primary) in a private network, administered NCA-TSCs that were active are
assumed to have remained active. Any unacknowledged user-user service requests
are assumed to be rejected, and administered NCA-TSCs which were in the
process of being established at the time of the switchover are dropped when the
switchover occurs. Those administered NCA-TSCs that were dropped are
reattempted again.
If a D-channel switchover occurs on a D-channel going to the public network then
all TSCs are dropped. A maintenance-provided “heartbeat” message periodically
is sent over each permanent administered NCA-TSC to ensure that such a
situation is detected and recovered from.
• Distributed Communications System AUDIX (DCS AUDIX)
The DCS over ISDN-PRI D-channel feature can be used to support DCS AUDIX.
(The connection between G3si and AUDIX should be BX.25.)
• GRS
GRS selects TSC compatible facilities when routing NCA-TSCs. In other words, a
NCA-TSC request can only select a routing preference that supports TSCs.
In a tandem node, GRS first selects facilities that support TSCs if the call falls into
any one of the following two conditions:
~ It requests a CA-TSC explicitly
~ It contains a DCS information element in the SETUP message
Once a trunk group with available members is selected, the call proceeds even if
all the TSCs belonging to the associated signaling group are active. In other
words, the completion of a call is given priority over DCS transparency.
• SDN
The DCS over ISDN-PRI D-channel feature allows the system to access public
networks such as SDN. SDN supports all DCS features except for the following:
~ DCS Attendant Control of Trunk Group Access
~ DCS Attendant Direct Trunk Group Selection
~ DCS Busy Verification of Terminals and Trunks
• Voice Terminals
An attempt to dial an extension that has been previously administered as
belonging to an administered NCA-TSC results in intercept tone being received.
Distinctive Ringing treats a call from another switch in a DCS arrangement as
external; DCS Distinctive Ringing treats such calls as internal. If both features are
administered, DCS Distinctive Ringing takes precedence. If EDCS is activated,
DID treatment may be different. See Example DCS configurations (page 329).
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Administration for Network Connectivity
CID: 77730 555-233-504 — Issue 1 — April 2000