It used to be (and may still be) that cell phones used a different language called WML (Wireless Markup Language). It's XML based, like XHTML, but simpler. You should Google around for cell phone language and WML and see if that's still the case. I have Elizabeth Castro's HTML for the World Wide Web 5th Edition (Peachpit Press, 2003), which has a whole chapter on WML. I would assume that there would be no problem with an account at LP serving up WML pages instead of (X)HTML or PHP, but it might not hurt to check if there's anything in the LP infrastructure that doesn't support WML (if that's what you still need to use).
P.S. I'm assuming that WML will support what you want to do with a cell phone, rather than having to go to some lower level protocol or download service. Re-reading your post, it sounds more like you want to push content to the phone, versus having the phone pull content from the Web. I don't know for sure if WML is involved in a push.