# Phone Number

Welcome to Phone Number on Exercism's C Track.
If you need help running the tests or submitting your code, check out `HELP.md`.

## Instructions

Clean up user-entered phone numbers so that they can be sent SMS messages.

The **North American Numbering Plan (NANP)** is a telephone numbering system used by many countries in North America like the United States, Canada or Bermuda. All NANP-countries share the same international country code: `1`.

NANP numbers are ten-digit numbers consisting of a three-digit Numbering Plan Area code, commonly known as *area code*, followed by a seven-digit local number. The first three digits of the local number represent the *exchange code*, followed by the unique four-digit number which is the *subscriber number*.

The format is usually represented as

```text
(NXX)-NXX-XXXX
```

where `N` is any digit from 2 through 9 and `X` is any digit from 0 through 9.

Your task is to clean up differently formatted telephone numbers by removing punctuation and the country code (1) if present.

For example, the inputs
- `+1 (613)-995-0253`
- `613-995-0253`
- `1 613 995 0253`
- `613.995.0253`

should all produce the output

`6139950253`

**Note:** As this exercise only deals with telephone numbers used in NANP-countries, only 1 is considered a valid country code.

## Source

### Created by

- @RealBarrettBrown

### Contributed to by

- @bcc32
- @Gamecock
- @gea-migration
- @h-3-0
- @mikewalker
- @patricksjackson
- @QLaille
- @ryanplusplus
- @wolf99

### Based on

Event Manager by JumpstartLab - http://tutorials.jumpstartlab.com/projects/eventmanager.html