Its too late when you have shut down at the gate, deplaneing the pax, as happened to us receintly.
On area the controller said "contact the twr xxxxx good day"
We had no joy and called area again, who said they would try the twr land line, no joy.
We conducted a visual circuit and landed making all calls as required.
After shut down, with the radio on to try for a new clearence, we here
Regional xxx, clear to land. we looked at each other and cracked up.
As it turns out buddy was out of the tower "chating" to some girls and thought that if he at least said something it would be recorded.
Well just another day in wally world.
IHD