Guys, I had Sprint and I checked out Cingular when I was ready to switch.
(You gotta check them out thoroughly because it doesn't make sense to switch very often -- even though Sprint sucked, I put up with them for years because of pricing, I owned the phone, etc.)
Sprint had TERRIBLE customer service. I turned dow a free phone with no contract that they offered me as I was leaving (already had no contract).
Cingular sounded good at first glance, but then I found out that their plans offer very little in basic service and beyond that, everything is extra.
Back to the topic. You should have an FCC notice under your battery or in the owners manual, saying what frequency your phone operates at (roughly).
From that, you can figure the wavelength, baased on the speed of light.
Generally, an antenna for any radio device should be a fraction or a multiple of the wavelength. There are other tricks we won't go into here, like the coils you see at the antenna bottom on car installations, etc.
Theoretically, you should be able to attch a straight piece of copper wire of the proper length, to the antenna or with a plug in the antenna jack, if it has one.
Your wife may not like this non- martha Stewart approach, but it could do the job.