The NFL is investigating whether text messages were sent to the Cleveland Browns’ sideline during games this season.

NFL spokesman Michael Signora did not elaborate to ESPN.com on Friday except to say the league is looking into the matter.

Texting would be a violation of the NFL’s rules prohibiting electronic communication during games.

Cleveland.com reported earlier this week that some coaches late in the season became angered when play calls were requested or suggested via text from the press box by a high-ranking non-coaching staff member.

The Browns and offensive coordinator Kyle Shanahan parted ways Thursday after reports surfaced that friction between the coaching staff and front office became an issue for the first-year assistant.

Cleveland.com said the text suggestion was one issue in Shanahan leaving the team. He perceived it as interference from the front office regarding coaching decisions. A source said the messages regarded personnel decisions and play calls.

The league’s electronic devices rule states:

“Unless specifically permitted by league rules, the use of cellular phones, smartphones, tablet devices, computers, wearable electronic devices such as Google Glass, and other electronic equipment by coaches, players and other club personnel is prohibited in club-controlled areas including, but not limited to, sidelines and coaches’ booths.

“These restrictions apply from ninety (90) minutes prior to kickoff through the end of the game, including halftime. Coaches, players, and other team personnel are permitted to use such electronic devices in the locker room prior to kickoff and are permitted to use league-issued Microsoft Surface tablets throughout game day for viewing coaches’ still photos.”