I'm developing a site that targets lower-end phones / internet plan subscribers, so I am trying to cut bandwidth use wherever possible. My question is this: on pay-per-kb or bandwidth-limited plan, is there a difference between upstream and downstream(in price, or how it counts towards the limit)? Or are the treated identically for those purposes? Does this vary by provider?

More specifically: if you click a url(.1kb), on a pay-per-kb phone plan, and that url sends you back a blank page (0kb), is your plan provider going to charge you for the event (.1kb)?