On Mon, 06 Jan 2014 20:52:27 -0800, Jeff Liebermann wrote:

whatever is wrong is at the base unit.

This is a good observation.

I picked up the Panasonic KX-TG6441 "Operating Instructions":
http://service.us.panasonic.com/OPER...TG6431-MUL.PDF

And the "Installation Manual" for the Panasonic KX-TG6441:
http://service.us.panasonic.com/OPER.../KXTGA740B.PDF

The frequency range is *below* the 2.4GHz WiFi range:
Frequency Range = 1.92 GHz to 1.93 GHz

And the claimed RF Transmission power is 115 mW (max.).