If you upgraded your iPhone to iOS 4.2 and you run any VoIP application in the background, the ringer will continue to ring even after the call is answered. Apps such as CounterPath's Bria, Line2, and other VoIP apps are affected. Apple is aware of this issue and has designated its status as 'severe'. Fortunately iOS 4.2.1 has resolved this bug, which also fixed some Wi-Fi issues with the iPad.H/T Todd Carothers
