The first time Bryan and I went to a bustling Chinese restaurant with a good Chinese friend, we were taken aback by how loudly he shouted at the waiters to get their attention. This particular friend was educated abroad and was normally soft spoken, so it seemed quite out of character for him to shout so loudly at anyone.
As we go to more Chinese restaurants, however, we find that at inexpensive to mid-range restaurants, shouting for a waiter or a waitress is more the norm than the exception. In fact, if you just raise your hand or call out quietly, you could be ignored for a very long time, as the waiters and waitresses at these huge and busy restaurants will not notice you at all unless you shout.
At first, Bryan and I were self-conscious and restrained about calling loudly. However, after a few futile attempts, we started calling "waiter" (fu wu yuan) quite loudly. Immediately, a waiter appeared and as we looked around guiltily, we saw that no other patrons had turned their heads to stare at us or disapprove of our "rude" behavior. Now Bryan confidently shouts for waiters' attention in busy Chinese restaurants but he always explains the custom to our Western friends first so that they do not wonder why he is being so impolite.
Explanatory Note:
Shouting for waiters is not necessary in every restaurant in China. You don't need to, and should not, call out in quiet restaurants and in expensive Western-style restaurants. In those places, the waiters are usually in closer proximity and are able to see your raised hand.
(selected from 101 Stories for Foreigners to Understand Chinese People by Yi S. Ellis and Bryan D. Ellis, published by China Intercontinental Press in 2012)