Arduino stop the loop
Don't do return loop(); With that you enter into a never ending recursion. No system can resist that.

See: return loop(); means "evaluate loop() and return whatever it returns". Well, loop is void; it doesn't return anything.

Even worse is the recursion problem: you call loop(), which calls CHIAMATA, which calls loop ... never ending. You blow out the stack.

I don't look any further than that. Probably there are more errors.