This has happened in my home when my children were younger. Rules were already established so if I ever saw one of them with a cell phone in their hand at the dinner table, I would know this must be an emergency call they're taking. Otherwise, they'd know better.
The rules I set were strict but simple and easy to follow with consequences that they understood as fair. I was a single parent so raising two children alone wasn't easy. It demanded a lot of consistency and patience. I didn't want to be their friend. I was their mother and father all rolled into one. I worked a lot of hours so I had to make sure they felt my presence at home even when I was not. That meant instilling fear that their actions would prompt a reaction from me.
Dinner table is for eating and talking to each other. It's where we bond on our daily experiences. The phone should be in your room when you come down to eat. Otherwise, you are disrespecting the family unit and everyone in it. It should not be in your pockets. I know some kids can text without looking. Please don't make me pat you down. I've done this. It won't be fun for you if I find something. If you have it on you, it will be taken away and you can skip dinner. Going hungry one night will never starve anyone. But you will remember to leave your phone upstairs next time.
Bedtime is for sleeping. You don't text while you sleep. When the lights go out, so should your phone. If I ever walk in and catch you in bed on the phone, you won't have a phone to go out with the next day.
If it continues, I will pull a Brady Bunch on you and install a payphone that takes quarters in the living room. When you want to call a friend, you call them on that. It's not cordless, so you'll have no privacy and the minutes run out when your change does. I don't believe in allowances so you have to earn your change by working for it, doing chores around the house at set stipends.
I always thought this was a great idea. Mostly because my parents used it on me when I would sneak on the home phone after they were asleep. No, we had no cell phones back then. Nothing is more embarrassing then calling your friends and saying, "Hold on, I need to put another dime in." Yes, I am that old, it took dimes.
You can still get a payphone online and have it installed to take change. If my kids weren't adults now with kids of their own, I'd have one put in just for humor. In fact, I may just get one anyway for the hell of it.