Inadvertent whistle

[Nevadaref]

Originally Posted by bob jenkins

The ball was still in TC, even if it wasn't in PC (or "posession.")

Use POI for an IW. Since there was TC, it goes back to A for a throw-in.

I concur. The only caveat with respect to the question asked by the OP is that the throw-in for team A will be at the OOB spot nearest to where the ball was located when the whistle sounded. This may not result in a throw-in on the endline. In this instance, where the original throw-in came from is not a factor in deciding from where to award the new throw-in.