Rule 1 – Section 4 – Article 2 – Players’ Numbering

d. When a player enters the game after changing his jersey number, he must report to the referee, who then informs the opposing head coach and announces the change. A player who enters the game after changing his number and does not report commits a foul for unsportsmanlike conduct. (A.R. 1-4-2:I)
PENALTY − [d] Live-ball foul. 15 yards from the previous spot [S27: UC-UNS].
Flagrant offenders shall be disqualified [S47: DSQ].