Then there is the odd occassion when a rest day may preceed an 0400 local report. The call on your rest day is to advise you the flight is cancelled...............
Oh well, Caller ID is a great thing, answering calls from work is not mandatory, but then niether are voicemails.
Like everything, its up to the individual and swings and roundabouts apply. There is no right or wrong thing to do.