Using analog inputs as digital

I am building a setup that needs at least 4 (preferable 6) digital inputs (microswitch) and uses also the arduino GSM shield.
That shield uses the digital pins 2,3 and 7 So there are not enough digital inputs left on the VMA05.

My plan was to use the analog inputs as digital inputs. This doesn’t seem to work when using the VMA05 board.

How can I solve this?