I totally POD JenJay. My kids do this, and I call back that I can't hear them, they'll have to come to me.
It's something of a pet peeve of mine, because my parents did this *all* the time to me as a kid. If they wanted me, they'd yell for me, interrupting what I was doing. If they really wanted me to drop what I was doing and do what they wanted, fine. But other times, when they just wanted to "see what I was doing" or ask me a question... I think that in general the person who wants the other's attention should be the one to go to the other.
In your case, I'd call back, "I can't hear you!" and then wait until they come to you. And ignore any "hiding" comments. The only thing I'd mention about those is, is it possible that your houseguests expect you to be focusing all your attention on them, like you might with short-term invited guests, and that they feel like you invited them over and then aren't present? If so, then you might want to make sure that they understand what to expect from the moment you extend the invitation: "I'd be happy to have you stay with us, but just so you know I do have a lot of work that I need to get done, so I'll need to carry on as usual for the most part." Or something.