I keep my phone in my pocket unless I am answering a call. (I used to keep my phone in a holster unless I was answering a call, but "smart" phones have an inconvenient form factor for that. So I've modified my wardrobe to include more shirts that can hold a smart phone in one pocket while all the usual things I've put in my primary shirt pocket for years can stay in that pocket.)
One of the most enjoyable aspects of dining with other people is the conversation over dinner. I would hate to miss out on that for telephone calls that I can answer later. Voice mail for the win.
AFTER EDIT:
Other comments here mention using phones in movie theaters. The response of the Austin Drafthouse theater in Austin, Texas is famous. The theater's video with a recorded comment from an ejected customer became a viral video on YouTube,
reported on in various news outlets. (The language of the video is rather crude, but it makes the theater's point that it doesn't want customers who use their phones in the theater.)
One of the most enjoyable aspects of dining with other people is the conversation over dinner. I would hate to miss out on that for telephone calls that I can answer later. Voice mail for the win.
AFTER EDIT:
Other comments here mention using phones in movie theaters. The response of the Austin Drafthouse theater in Austin, Texas is famous. The theater's video with a recorded comment from an ejected customer became a viral video on YouTube,
http://www.youtube.com/watch?v=1L3eeC2lJZs
reported on in various news outlets. (The language of the video is rather crude, but it makes the theater's point that it doesn't want customers who use their phones in the theater.)