I carry a 500 min. AT&T prepaid phone card from Sam's Club. The "per minute" charges are very low with the high minute cards. I use my cell phone for all our long distance. However, there are times that I don't have service, such as at some of the more remote camps the Scouts go to. AT&T charges extra minutes to use the card at a pay phone. Considering that it is just an emergency back up, I don't worry too much about it. The minutes never expire and there is no minimum usage requirements. I have had my card for close to 8 years with no problems.