128 Alternative Call Routing for Network Bandwidth Management
Figure 48 "Example of Alternative Call Routing for NBWM in operation"
(page 128) shows a diagram of a typical network where Alternative Call
Routing for NBWM can be used. It illustrates the sequence of events that
are explained in the information following the diagram.
Event number 1 pertains to the originally dialed call that experiences low
bandwidth or unacceptable QoS conditions. Event number 2 pertains to
the alternately routed call.
Figure 48
Example of Alternative Call Routing for NBWM in operation
There are multiple choices of alternate routes provided for the overflowed
calls. Network administrators who do not want calls to be blocked, but
have a limited amount of bandwidth available, want to overflowcalls
to conventional trunks, (Public Switched TelephoneNetwork [PSTN] or
TIE/Meridian Customer Defined Network [MCDN]). This feature allows
calls to be routed by overflowing them, trading off the capital cost of WAN
bandwidth against the incremental cost of overflowed calls.
Nortel recommends that this feature be used with DID (Direct Inward Dial)
numbers. This allows calls that are rerouted over the PSTN to ring the
intended telephone directly. It is possible to user this feature without having
DID such that when the call gets rerouted over the PSTN the call reaches
an attendant console or a specific telephone.
When there is insufficient bandwidth for a station-to-station call, the
Alternative Call Routing for NBWM feature uses a trunk for a call which
would not normally use a trunk.
Prior to the introduction of the Alternative Call Routing for NBWM feature,
there was no alternate routing mechanism for the following types of
station-to-station calls:
•Branch Office calls to or from the main office
Nortel Communication Server 1000
Branch Office Installation and Commissioning
NN43001-314 01.02 Standard
Release 5.0 20 June 2007
Copyright© 2007, Nor tel Networks
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