The actual analysis itself makes it clear that the research specifically on cell phone bans is lacking. In particular, of the 1317 studies, only 22 were relevant, more than half of which were Master Degree research projects, not peer-reviewed studies. It's fair that the evidence for cell phone bans in schools is inconclusive, but that's because there isn't enough quality reach yet to draw conclusions.

I was actually referring above to studies on cell phones in general for task success, non-specific to schools.