I gave it the simplest case I could think of... no data connection at all. used N900's CONTACTS used "call via QGV" (wait a minute...) still trying to call... hit "Cancel" button.... Received call failed and call canceled messages. waited 15 minutes tried to make another call. Received "another call is in progress. please try again later." established a Wifi connection, waited 15 minutes tried to make another call. Received "another call is in progress. please try again later."