It's common for people to lose a mobile phone. We bring them with us everywhere, they go in and out of our pockets all day long.
What's not common is how much we rely on those phones for one very critical step: authenticating ourselves for our online accounts.
While there are different methods for proving to a web site that you are who you say you are, text messages with confirmation codes remain one of the most popular techniques for authentication.
If your phone is gone, someone can pretend to be you for "recovering" your account access, even though they are not authorized to do so. It's critical that if your phone goes missing that you tell someone that you work with immediately, including the technical / IT team. This will help them reset 2-factor authentication techniques until you can either get a new phone number or retrieve your lost device.
A lost phone is an annoyance. A stolen identity is way, way more inconvenient. Speak up if you're missing your device. It may save you considerable aggravation later.