I have T-mobile prepaid which I use only very occasionally and never for the Internet (although as others have pointed out you can get access on a 24-hour basis). I have a Clearspot wimax modem (very small, http://www.clear.com) which I use for Internet access. It supports up to 8 wireless devices plus you can connect via usb (but I've never connected the N900 by usb). Clear is owned by Sprint and provides the 4G access for Sprint cell phones. But you don't need Sprint, just a Clear account.