The first sign is if you check your phone constantly, not necessarily for missed calls, but text messages, status updates, e-mails, push notifications, etc.
Second, your checking becomes so frequent you develop “checking habits” or the urgency to update or check certain applications such as Facebook, but within 10 minutes of each other. Most “checks” don’t last more than 30 seconds, but it’s the constant glancing down at your phone screen that classifies under this behavior.
Third, you can’t roam around your house or office without having your phone with an arm’s reach.
Another sign of possible addiction is not being able to leave home without your phone. Some people describe it as “being lost” without their phones.