# Introduction

You've joined LinkLine, a leading communications company working to ensure reliable connections for everyone.
The team faces a big challenge: users submit phone numbers in all sorts of formats — dashes, spaces, dots, parentheses, and even prefixes.
Some numbers are valid, while others are impossible to use.

Your mission is to turn this chaos into order.
You'll clean up valid numbers, formatting them appropriately for use in the system.
At the same time, you'll identify and filter out any invalid entries.

The success of LinkLine's operations depends on your ability to separate the useful from the unusable.
Are you ready to take on the challenge and keep the connections running smoothly?
