The LL rule is as follows. It applies only in LL.
Part of 3.17 The use of electronic equipment during a game is restricted. No team shall use electronic equipment, including walkie-talkies, cellular telephones, etc for any communication with on-field personnel, including those in the dugout, bullpen, or field
Penalty: If, in the umpire’s judgment, any player, manager or coach uses an electronic communications device during the game, the penalty is ejection from the game. NOTE 1: A manager or coach is permitted to use a scorekeeping and/or pitchâ€counting application on an electronic device without penalty, provided such device is not used to receive messages of any sort..
MLB has a similar ban but it's in the MLBUM. The latest one doesn't have the non-rules sections and my other one is 10 years old so I don't want to copy something that might have changed/