Type “long distance phone service comparison” into Google and check out a few of the “objective” evaluation sites. We are in the middle of doing that today. There seem to be a few no monthly fee services that are cheap. Zone LD is one of them, but a few more we are checking out now.
Another option is to go to Costco and buy a MCI calling card which provides 3.5 cent per minute calls. You have to program your phone to pre-enter the access number and codes, but Consumers Reports recommends this approach.
The problem with not designating a long distance carrier to your local phone company is that you are then at the mercy of any company if and when a visitor to your home makes a long distance call by the usual means. A random but "permanent " designation process then gets triggered.
Cell phones can be good to urban areas, depending on your carrier. Because their use is limited to a single phone, we don’t use them much for long distance–we like having an extension phone for our young kids to speak to their relatives on.