Sound ops are generally only on cans at top of show and out of interval. At least on complex shows where they need to clearly hear the room (small shows with a couple of actors delivering spoken word claiming they need both ears is bull). Generally the issue of lack of communication is solved by giving them a copy of the script (or rather the sound designer a copy of the script) which they use to create a mic plot and cue list. Add some cue lights for any cued sound FX or Off Stage Dialogue, Bobs your uncle.
If you are really worried about being in contact with your Sound Op, get a flasher for your comms set - basically it is a big light that you loop out of the comms beltpack. It lights up and flashes whenever someone presses the call button. More complex shows, we tend to put a second comms beltpack at AX, however instead of a standard headset, we use a clearcom "Phone" handset, so that the sound guy can jump on and off comms quickly.