That's a great suggestion Jeff.
Maybe these other DECT phones in the same house: http://farm3.staticflickr.com/2873/11811729095_cafdd2467b_o.gif
Are causing the problem with this DECT phone: http://farm4.staticflickr.com/3779/11811980883_f540a29bee_o.gif
It might also be the batteries, although you can see in the previous photo that they are fully charged - yet - I charged them today off the Panasonic base: http://farm8.staticflickr.com/7341/11829684174_606aa41376_o.gif
And, strangely, when I ran the registration procedure, they showed up as being discharged! ????????? http://farm8.staticflickr.com/7331/11829272305_f01a1c8679_o.gif
So that makes absolutely no sense. I chalk it up to "confused electronics" at this point - because I can't imagine what happened to make a fully charged battery indicate almost discharged.
Anyway, as a precaution, I ran the re-registration procedure, which is described on page 27 of this PDF: http://service.us.panasonic.com/OPERMANPDF/KXTG6431-MUL.PDF
This is a snapshot of the re-registration procedure: http://farm8.staticflickr.com/7353/11829263895_ac761cd5cf_o.gif
Since the menus don't show up until *after* you run the procedure, I post below sequential screenshots so others who run the registration procedure can see the cause and effect on the phones:
Press LOCATOR on base 4 sec. Then press OK. http://farm4.staticflickr.com/3708/11829267845_c9363aba09_o.gif
Call from Base: http://farm8.staticflickr.com/7392/11829686934_e1799e3098_o.gif
Base regtr'ing http://farm8.staticflickr.com/7331/11829272305_f01a1c8679_o.gif