I have the same problem with my phone. As I am listening to the other person talks, it will fade in and out (almost as if someone pressed the mute button for a second or 2). I also have a lot of dropped calls. At my house I usually get 1 bar at 3g and it often will switch to 1x.
I did some research and found out I am 4.97 miles from the nearest verizon cell phone tower. There are a couple of T-Mobile and US Cellular towers within a couple miles of my house. I talked to verizon on the phone as well as went to a store and was told the same information. It was suggested that I buy a network extender for $250. I told them this is more then I paid for my phone.
One of my friends comes over to my house and always has issues getting reception in my house. I didnt think much of it and thought because he has a cheap flip phone, it might not get the reception of a higher end phone like the droid.
It is strange, I had sprint for 10 years before switching to Verizon and never had reception issues in my house with my old windows mobile phone. I switched to Verizon because I wanted an android phone and didnt care for Sprints selection of phones at the time I bought my motorola droid.