Don't use your phone when having a meal with someone. Ideally, you should turn it off entirely. If you're anticipating an important call, let the person you're with know beforehand that you're expecting a call that you'll need to take. No matter what, don't hold a conversation at the table; step away, follow step 1, and don't stay away any longer than you would for a bathroom break. Never text at the table, even if the face-to-face conversation dies down. It will be seen as disrespectful.