I have observed a sudden increase in dropped calls over the last week. I used to rave to my friends about no longer having dropped calls, but the last week has been incredibly frustrating. I rarely get to 20 minutes in a call without it dropping.
In case it helps, I'm making calls from my apartment, I'm in zip code 10014, I have the iPhone 4S, and I have 5 full bars on the signal indicator.
We are having the same issue with dropped calls. I have an IPhone 4S and my husband has an IPhone 4. This has become increasingly worse. We never had these problems in the past. We have updated our software and towers but nothing helps. Something is going on with the signals!