Voice over internet protocol call fallback for quality of service degradation

摘要

The invention provides a way to fallback to a PSTN call at any time during a VoIP call when Quality of Service in a VoIP network falls below some acceptable level. The PSTN fallback calls can be retrieved "midcall" and rerouted back over the VoIP network. This provides optimal utilization of VoIP without sacrificing the quality of the call connection. Calls are cheaper because PSTN fallback calls are only established temporarily for the amount of time that the QoS problem exists on the VoIP network. Call fallback is conducted in a VoIP gateway by first receiving an incoming call. A Voice over IP (VoIP) call is established for the incoming call over the VoIP network. VoIP packets are encoded from the voice signals in the incoming call and sent over the VoIP network. Quality of service of the VoIP network is monitored during the VoIP call and a fallback call is setup over a PSTN network at any time during the VoIP call when the monitored quality of service of the VoIP network degrades. For a time the voice signals from the incoming call are cross connected to both the output for the fallback call and the output for the VoIP call. When a destination gateway starts receiving the voice signals from the fallback call, the VoIP call is dropped. The quality of service on the VoIP network continues to be monitored during the fallback call. A new VoIP call will be reestablished over the VoIP network during the fallback call when the quality of service of the VoIP network improves. Voice from the incoming call is for a time again cross connected to both the fallback call and the new VoIP call. After the destination gateway starts receiving audio packets again over the new VoIP call, the PSTN fallback call is terminated.