I am setting up a 3300v with 4 x FXO ports and 4 x FXS ports.

I want to set it up so that if the VoIP connection is lost, calls from phones on the FXS ports are automatically sent to the FXO ports (ie to the PSTN).

I have found how to force calls to the PSTN (by dialing the FXO port number and adding #), but cannot see how to make this happen automatically if the VoIP connection is down.

Does anyone know the answer to this? I could not find anything in the manual or the application notes, and various Google searches did not provide anything very useful.

David