I don't think carriers forced BlackBerry to stop requiring a BlackBerry data plan. So long as no special equipment (servers, etc.) is needed on the carriers' end it makes zero sense for carriers to even be involved in whether BlackBerry charges individuals for BBM or any other service it may offer. Any carrier charging BB10 users for BIS when the carrier itself incurs no extra costs is gouging, maybe even committing fraud. It's double billing, no different from double billing medicare or some plumber showing up at someone's house and charging for work he did and also charging for other things he has nothing to do with like water delivery or the water itself.