I work at Berger King at airport. Usually my work is making the hamburgers, but sometimes they give the cashier shifts, and we still have this old way, where you need to shout for the customer by saying the order. Sometimes I got block with the first letter, but the place is very crowded, so no one really notice, but of course they'll never answer with the first call so you do it again. Then I developed this way of, giving the order straight away to the customer before taking the next customer's order if the order is ready, or keeping an eye contact with customer, and when his order is ready, I make a gesture the customer comes and takes the order. But it only work if the customer is really waiting for the order, most of them go and take a sit, and our place is really big and crowded.