Calls are ever so slightly choppier now that I switched from my LG enV3 to the Droid. I live in an area that is supposedly covered fully by Verizon but no service in town really gets good service here (and no, I don't live in a valley, on the outskirts, or in the middle of nowhere).
So we bought a network extender and were initially pretty skeptical about it (think eBay antenna extenders) but to be honest it moved our phones from 0 bars and rarely able to make/stay on a call to full signal at all times (for voice not data).
I know it seems to be working because I hear the tone it makes when I start a call, but yet the reception/signal strength on my Droid is like one bar. I know that bars don't necessarily mean anything but when you are talking one bar with a simulated cell phone tower RIGHT next to the phone, there is no reason to have one bar.