It's not quite on the level of the infamous Roy Keane presser, but that doesn't mean it gets a pass.
It doesn't disrupt the interview nearly as much, and the people cut off don't take it as badly as Roy did, but the fact that it's not a journalist's phone that does the ringing is the problem.
Why? Because it's the phone of the media officer, who you'd think would know better than to leave their phone on load, but sure how and ever.