Some people think that the cell phone ban in sports books has to do with the federal prohibition against transmitting gambling info over phone lines. But that's not the reason. What it has to do with is messenger betting.
Sports betting syndicates used to station people in sports books around town and when they wanted to bet, for example, $50,000 on a game, they'd call up the "beards" at each book, who'd then bet the max the sports book allowed. By having 10 people, say, betting $5,000 each simultaneously, the syndicate could get the $50K down before the line moved in response to the big bet.
Sports books complained to the Gaming Control Board, which put into place a number of rules, including the ban on cell phones in sports books.
It's a particularly ineffective countermeasure. If you walk through talking on or listening to a cell, a casino employee will tell you to turn it off. Of course, it's easy enough to stand just outside the sports book and use your cell phone all you want.
