Timeout question!

[MOofficial]

Veteran guys, Need your help!

Team B takes the ball out of bounds, after team a made a lay up. Team B gets the ball in bounds, but as soon as a player from team b receives the ball, he is trapped. While he is looking for someone to pass for. Me and my partner hear a time out being called on the bench. We give them the timout, but the coach from Team B says he was not the one that called it and he does not want one, so it should be an inadvertent whistle. My partner and I discuss it and just rule it an inadvertent whistle and bring both teams back out and play ball. I know we missed this one, but what would the correct ruling be? Thank You