More often than not, and especially in a crowded gym, it is difficult to hear the score or whether a ball has been called in or out. We think that this YouTube video is a good review of hand signs for both scoring and line calls. Also don't forget that if you use "partner communication" to warn your partner that a ball looks like it's going out ("out", "watch" or whatever you and your partner use), you still need to make the call if it does go out - hand signal, verbal or both! Also, don't assume players can see whether or not the ball is in or out, especially if you are concentrating on hitting the ball, as you should be, or 40'+ away...
Daniel J Howard provides a brief tutorial on using hand signs for scoring and line calls
