I mostly shoot with voice activated traps, and a fairly loud "Pull" works best for me.
If you have a puller, and if he is also keeping score, you have to slow things down a bit so he has time to write down the score. I've done the pulling a couple of times when our microphones weren't working as they should. It's a boring job, and its easy for your mind to start thinking of something else and miss a call. Also, you can be so intent on not missing a call, you end up anticipating the shooter and sending the bird out early. Then there are the guys who whisper pull and expect the bird to come out. I don't mind keeping score, but I'd rather be a shooter than a puller.