Talking on the phone while other people are around is rude, yet often tolerated and to some degree expected amongst professionals. The worst embodiment is when someone takes a call in the car with other people, who are essentially taken hostage because they can't go anywhere and they can't talk to each other or listen to music.
While I understand that sometimes it's unavoidable, it should be a last resort. If possible go to another room, so the people around you can continue their conversation. No one should be given free license to disrespect other people's time. The fact that it's a work commitment is a poor excuse.
Do your best to focus on the people around you. There's no need to multitask people, especially if they're going to be forced to wait until you're ready to re-engage with them.