Consumer Cellular is an AT&T reseller. They use AT&t's towers and network.
Have been with them for about 4 months now. Switched from an AT&T account. Went from $68 per month to $32 per month (for two of us).
No long term contract required (month-to-month). Can use just about any phone that is AT&T compatible or buy direct from Consumer Cellular at reasonable (I think) prices.
Double check with Consumer Cell on the AT&T phone as there are some models that will not handle the change over without doing a few extra things.
Found Consumer Cell service to be very good. Lots of questions on my end when thinking of changing. They were very helpful and I felt honest about what I wanted to do and how I wanted to do it. All was handle to my satisfaction.
Live in Oregon and spend time in the greater Portland area, the Oregon coast and up into Washington around the Mt St. Helens area. Have not had any problems with coverage.