Change my smartpohone rate plans

I have $60 monthly unlimited with data plan on my galaxy go phone.

I was thinking about to change $25 monthly with 250 min and unlimiited text (or pay per use plan if available) since I'm currentry out of the U.S. but wanted to keep the same number with lower costs.

• I couldn't find way to change my rate plans on line.

     Here are instructions on how to register online to manage your GoPhone          

     Account: http://www.att.com/esupport/article.jsp?sid=KB92523#fbid=t9mjtZs2WYs

• Also, couldn't reach 611 to change your features from out side of  the U.S.

     Error message: Emergency calls only

I would appreciate some further assistance in sorting this matter out.  Thanks.