Sprint will soon begin a promotion in which customers can trade in any iPhone model and receive $100 off an iPhone 4S in return. TechnoBuffalo reports that starting May 18, Sprint will offer $100 on any iPhone trade-in—assumedly including the original model—towards a new iPhone 4S. The offer will reportedly be available for current and new customers alike, but requires a new line of service and a two-year commitment. According to the article,…
