batt died, phone still rang then to voicemail

[rifleman wi]

Trying to see if anyone else experenced this. My batt died, my wife called while phone was dead, it still rang 2 to 7 times before voicemail picked up insted of going straight to voicemail. Phone died during the call with her. Anyone else experence this? Its really weird.she also has a moto droid, and we couldent recreate what happened. Thanks in advance.