Why not an X10 wireless phone.
An 5.8 or 6.0 GHz phone that can except several handsets and doesn't interfere with wireless cameras. As a plus.. X10 could add a couple features like a TV/audio receiver MUTE Button. So a person could pick-up the phone and mute the TV with the same hand. And a couple X10 RF On/Off buttons.. so when you get that call late at night you can turn on a lamp with the same hand.
X10 could even have a several base units available too. Besides the normal message recorder... why not options like an X10 triggered dialer that would call out when you push the button on the heart-shape thingy. Or the X10 unit that allows users to call home and control X10 devices.