This won't end well...
There will definitely be TM issues if you create any type of cellphone related website. Big companies do not worry about legal fees and will take down any site that may or may not affect them. If you make a site of a completely different nature, I have a feeling they will still send you a C&D letter. The only way you could win (IMO) is if you registered this before the company was made (or at the same time) and your site was non-cellphone related.
I'd say reg fee, if not negative reg fee since having this is more trouble than its worth.