I have used pocket mail service for a period of 3 months during my vacations last summer - As long as you are in the United States where public phones are very accessible, I find this way of communication extremely interesting and cheap; You are limited to 4000 characters per message but you can send and receive as many messages as you wish. There are various plans sumitted by pocket mails and the service is very good. If you are going out of the USA, for example in the Bahamas or Caribbeans, we are talking differently and it might end up extremely costly, which friends are actually experimenting -