Page 128 of 258 Alternative Call Routing for Network Bandwidth Management
Figure 41 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 41
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 overflow calls to conventional trunks, (Public Switched Telephone Network [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 use this feature without having DID, so that when the call gets rerouted over the PSTN the call reaches an attendant console or a specific telephone.
