The following is a hypothetical situation. A friend of mine wants to replace his/her existing iphone (which he/she bought few months ago) with a new 3G version. The old iphone has been activated through itunes and was used under a plan with AT&T. How can I use his/her old iphone as a regular cell phone without having to participate in a new AT&T plan, i.e., keep my old plan and just replace his/her sim card with mine.
NOTE: The Ziphone software was downloaded to the iphone to enable the user to add new applications. Ziphone was added to an activated iphone. The iphone remained activated under the AT&T plan even with the downloaded Ziphone software!