Fun with phones, not Most of the 1xRTT phones can do both 1xRTT and fallback to "normal" operation. I'd think the 120e could do both, but then I don't have one.
Looking at thesuplynet.com's site, I only see a cable listed for the 120C, and not the 120e- have you contacted them to make sure the pinout is the same for both phones?
-------------------- Lisa Gade Editor in Chief, MobileTechReview