want more range, here is a way to increase it that has worked for me.
Buy a Radio Shack #270-1412 "replacement telescoping antenna" for $3.49
Remove the bottom section (screw) and substitute the remaining section
for the factory base antenna. Fully extended, the new antenna is about
3X longer. Connection is mechanically identical to original antenna.
Other methods that involve coax or longer wavelengths can detune the
multiplexer, but this mod works very well. And of course, get the base
unit as high as possible.
BTW, if you normally experience a "hum" in the audio, be sure the base is
not sitting on a metal surface.
P.S. - If you have any comments to share about this phone, please email
me. Exploring this product has become a hobby with me.