I hear it quite often.
If that's the case, you don't have to answer the phone - especially if you're in a meeting or with someone.
Good meeting etiquette and showing respect to the person/people you're with is that you prioritise them over anything else - especially interruptions from a phone call.
Is the interruption more important that the person you're with or the task you're working on? If it is - fine, go ahead and answer it but let them know. If not, let it go through to voicemail and call them back when it's more convenient and you're free to talk.
If you're expecting an urgent call - say so. Otherwise, remember to switch your phone off or put it on silent when you're with someone.
(Photo credit: plenty.r.)