AT&T chief Randall Stephenson in an event at Mobile World Congress on Tuesday called for a system that let users keep app ownership across platforms. He argued it was frustrating that buying an app on one platform didn't give you the rights to the app on another. He saw solutions such as the Wholesale Applications Community (WAC) or HTML5 as being better models, although few phones actually support WAC or use HTML5 in a major way for apps.