PSTN fallback using dial on demand routing scheme

A VoIP gateway, comprising:

• a telephony interface for receiving an incoming voice call;
• a VoIP interface for encoding the incoming voice call into VoIP packets;
• and sending the VoIP packets over a VoIP network;
• and
• a controller that establishes a fallback call with an endpoint over a circuit switched network and then redirects the VoIP packets from the VoIP network over the fallback call;
• a voice activation device that detects silence periods in the incoming voice call;
• and
• a switch that switches an active channel from outputting VoIP packets received over the VoIP network to outputting VoIP packets received over the fallback call when the silence period is detected.

An electronic storage medium for storing software for controlling calls in a network processing device, including:

• code for detecting an incoming call;
• code for monitoring quality of service of a VoIP call that transmits VoIP packets containing audio for the incoming call;
• code for initiating a fallback call over a circuit switched network to a destination endpoint when a low quality of service condition is detected on the VoIP call;
• code for redirecting the VoIP packets from the VoIP call to the fallback call during the low quality of service condition;
• code for establishing another fallback call over the circuit switched network to a different destination endpoint when there is insufficient bandwidth on the already established fallback call;
• and
• code for conducting a multilink point to point protocol session using both fallback calls established over the different destination endpoints.

An apparatus for controlling calls in a network processing device, including:

• means for detecting incoming calls;
• means for monitoring quality of service of VoIP calls that transmit VoIP packets containing audio for the incoming calls;
• means for initiating a fallback call over a circuit switched network when a low quality of service condition is detected on one or more of the VoIP calls;
• means for redirecting the VoIP packets from one or more of the VoIP calls to the fallback call during the low quality of service condition;
• means for detecting when the low quality of service condition no longer exists on the VoIP calls;
• means for starting a drop call timer;
• means for bleeding VoIP packets from the incoming calls from the fallback call back to the VoIP calls when the drop call timer expires;
• means for repeatedly bleeding VoIP packets for other incoming calls from the fallback call to the VoIP calls by first waiting for the call timer to expire and then verifying that the low quality of service condition no longer exists on the VoIP calls;
• means for repeatedly bleeding VoIP packets for all remaining incoming calls from the fallback call to the VoIP calls as long as the low quality of service condition no longer exists on the VoIP calls;
• means for starting a drop link timer when all incoming calls have been bled from the fallback call;
• and
• means for terminating the fallback call when the drop link timer expires and the low quality of service condition no longer exists on the VoIP calls.