I'm not entirely sure of the terms of service for Go Phone, but my guess is that regular Cingular reception is identical to that of a tradtional monthly subscriber. The difference may be when you are out of the native cingular area. If you are out of the Cingular area you may not have any service or you may pay a considerable amount to roam on another carrier's system *if* a roaming agreement is in place. If no roaming agreement is in place you'll only have access to emergency (911) service.
I've not bought Cingular refill cards but there *may* be local sales tax on the amount of the card. Any other "surcharges" are already included (USF, 911 fees, county/city/fed taxes etc.) Other than that you will not pay any other taxes.[TELECOM Digest Editor's Note: I have noticed here that Cingular Wireless prepaid phones (although I used to have AT&T prepaid until they were bought out) is different than 'regular' service. Here in our town, they are still going with the mechanics of AT&T Wireless (for prepaid) and treating us like 'roamers' because that is what AT&T did with us. No matter I guess, since it is 25 cents per minute for either local or roaming on Cingular Prepaid service here. PAT]