One think that has always kind of bugged about Trek, and I'm talkin about TOS, TNG, DS-9, Voy and Ent. When they hail another ship, if the other ship does not respond within a second or two, the communications officer tells the Capt, no reponse to our hail 
It's kind of like us making a phone call and if the person we are calling does not pick up the phone on the first ring, we assume that they are not home and hang up, whats up with that...

It's kind of like us making a phone call and if the person we are calling does not pick up the phone on the first ring, we assume that they are not home and hang up, whats up with that...