If anyone lists themselves as "Smokes occasionally" or "Trying to quit" it almost always means "I smoke quite a bit and don't truly plan to stop. I just know a lot of people wouldn't ever go out with me if I listed myself as "Smokes Regularly/Frequently" so I lie even though everyone knows I'm lying."
Unless there's some sort of emergency (or you are genuinely trying to send the message that you are not at all interested), just put the phone away and do not make or answer any calls. It shows you really aren't all that interested in making any sort of good impression and that you can't even focus on your date completely even at the point when you're supposed to be showing your best side. Whatever it is... it can wait... Or- just go to the bathroom if you truly need to make a call or read a text message. Spare your date the uncomfortable stare into nothingness, as you engage in conversation with someone else, at the very least...