Nortel Networks Corporation

Weilin W Wang

Joyce A Bradley

Andre A LeBon

He Huang

Eugene E Margulis

Roque M Ip

William C Leung

Anton Driesse

Syed Ayaz Ahmed

A telephone network includes an Enhanced Call Routing (ECR) function that reroutes calls when the high usage route and fixed tandem routes are overloaded or otherwise unavailable. The ECR function tracks the operation of the telephone network on the basis of origination switches and destination switches and provides temporary network rerouting during outages and unusual loading situations. Further, the ECR function supports Local Number Portability (LNP) so that it may operate in those telephone networks that are designed and/or modified to support LNP. The ECR function resides on a signaling network element such as a Service Switching Point (SSP) and/or a Service Control Point (SCP). A call setup request is received by a Service Switching Point (SSP), an origination switch in the traffic network, and intended for a destination switch. Initial routing via a high usage route and fixed tandem route(s) are unsuccessful. The SSP sends a Network_Busy message to the STP/SCP supporting the ECR function. The ECR function then attempts to determine an alternate tandem route for the call. If successful, the ECR function directs the SSP to route the call along the alternate tandem route, the alternate tandem route either being via the telephone network or via an alternate telephone network coupled thereto. If not successful, the ECR directs the SSP to send the call to a resource for caller notification. In another operation, the ECR function monitors the number of Network_Busy messages received for each originating switch/destination switch pair in the telephone network.

Enhanced call routing in competitive local telephone networks

A method for handling congestion in a communication network, known as a focussed mass calling event (MCE), occurring when the rate of calls to any given terminating number increases dramatically resulting in a large number of incomplete calls directed towards that number, known as ineffective attempts. Switches in the network operate under control of a network processor and ineffective attempts are logged and monitored by the switches. If the number of ineffective attempts on a switch for a particular terminating number exceeds a threshold in a given sampling interval, an MCE is detected on the switch and reported to the network processor along with the terminating number. The network processor responds by periodically broadcasting a gap control message to all the switches of the network identifying the congested terminating number and a gap time. The switches respond to the gap control message by placing a guard-time between calls to the particular terminating number based on the gap time. The switches also periodically report on the number of blocked and passed calls to the MCE terminating number which information is used by the network processor to adjust the gap time in the gap control message. This process continues until the congestion at the terminating number is alleviated.

Mass calling event detection and control

A method of accomplishing switchover from an inservice local to a remote NP (Network Processor) is described. The remote NP is periodically updated with configuration data obtained from the inservice local NP. Switchover from the local inservice NP to the remote NP is initiated. Communications between the remote NP and a plurality of NEs (Network Elements) is established nonsynchronously. The local NP is notified that the remote NP is established as an inservice NP.

Methods and systems for emergency routing restoration

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Plano, TX, United States of America

Weilin W Wang