Samsung Galaxy A55
It's not possible to make voice calls
Solution 1 of 11: Flight mode is turned on
You can turn off all wireless connections so your phone can’t cause any interference with sensitive equipment in a plane or a hospital. You can use many phone functions when flight mode is turned on, but you can't send messages or make calls.
Slide two fingers downwards starting from the top of the screen.
Press the flight mode icon to turn the function on or off.
Press the Home key to return to the home screen.