Roaming works on Chinook Wireless...
...but will AT&T cancel your contract if you are constantly roaming? There were rumors that Cingular would do so, but I have not heard anything about the "new" AT&T.
I have an iPhone and presently live in Chicago. I may be moving to Montana, where they do not offer AT&T service, but they do have GSM service that you can roam on. It works fairly well -- I roamed on it with my iPhone when I was there last month.
I can maintain my billing address in Chicago, because I have a business address located in Chicago. Therefore, I would not have to inform AT&T of my move. Would they nevertheless cancel my contract because I am roaming too much?