It does this because PBXs are generally programmed to forward busy or unanswered calls to another extension .
After a certain number of rings , the PBX stops ringing Fred 's extension and forwards the call to an extension connected to the voicemail system ( C ) .
PBX does this because PBX are generally programmed to forward busy or unanswered calls to another extension .
After a certain number of rings , the PBX stops ringing Fred 's extension and forwards the call to an extension connected to the voicemail system ( C ) .