I believe she needs hands-free so they can play games at the same time, as she mentioned.
OK Sorry.
Guess I missed that part.
Seems to me that I have seen hands free advertised as a feature on some GMRS walkie talkie radios. I forget how it works exactly and never paid much attention to it, because I never saw any reason to use it.
Maybe somebody else would have more knowledge about that.
You don’t have to replace your existing phones, just simply buy the uniden system and plug the base station into a spare phone jack. Then, you can use the intercom system and still use your existing phones for everything else.
Yes, I guess I could try the second phone system setup.
DooWahDiddy is right; when three monsters jump you and you’re doing everything in your power to keep alive, picking up the phone/walkie talkie/etc to talk isn’t going to happen. I’ve used push-to-talk and Teamspeak before, and I can handle it OK, but Mr. Athena is just learning and he’s overwhelmed by just the game at this point. Plus he’s a perfectionist - small echos or having to type a couple keys don’t bother most people, but they drive him batty, as does the half-duplex stuff. I have a high maintenance husband 
I’ll try Google Speak; that sounds like it may be the ticket. If not, I’ll look into the phones.
If that all fails, Amazon has some Panasonic phones (5.8 ghz) that have the features you are looking for, that work with headsets:
http://www.amazon.com/gp/product/B0007Q3QQM
I’m thinking about this system but will probably want to test drive it first. But it is available from Target, and I could return it instore, which is a plus.
That page also has the instruction manual linked (PDF) for you to peruse further.