Here is a quote from Cingular's website re: the merger. Note they talk about GSM service, not just "regular" cell service.
With Cingular’s GSM service, you now have access to the largest digital voice and data network in America. We call it the ALLOVERSM Network*, giving you more signal bars in more places.
Cingular’s Nation® Plan is the only simple-to-understand, nationwide plan that allows customers to roam the country, while paying the same low rate.
GSM is the global standard for wireless technology, so you can stay in touch around the world. GSM technology uses a SmartChipTM, which allows you to move your phone book from phone to phone without reprogramming.
If you don’t have Cingular’s GSM service, learn more about our Cingular Nation® Plans.
Depending on where you are in Wolfeboro, even within a few blocks, a cell signal can vary considerably. It's a terrain thing coupled with a lack of towers and whose service you have (A side or B side).