When one rings a phone number that is busy, is it not rather pedantic and contrived to be told “Il-persuna li qed iċċempel ma tistax tirrispondik bħalissa” (the person you are calling cannot answer you right now) or else that “Il-klijent li ċempilt mhux disponibbli” (the client you called is not available)?
Why not the more straightforward “Dan-numru okkupat” (this number is busy)?