Earlier this year I purchased my own router and modem and when I called Spectrun to cancel my rental, I was informed I needed to sign up for a new package - the price of which was about $2 more than I was previously paying WITH rented equipment
It was a pretty blatant move to push customers off of grandfathered plans. For example this was about 10 years ago when iPhones were becoming popular, and at the time at least there were iPhone specific features for data plan and visual voicemail. So someone upgrading to an iPhone would be forced to give up any grandfathered plans on their account.