A statewide ban on cell phones in public schools took one step closer to becoming reality Thursday, when members of the state Senate overwhelmingly approved legislation that would implement such a ban. Bans on school cell phones are gaining momentum across the country, and that growing support is present in Massachusetts as well. Seven individual bills were filed by senators at the beginning of the current legislative session that would implement some form of school cell phone ban. Last session, not a single bill to that effect was filed with the education committee, according to Sen. Jason Lewis.