# Phone Number

### Overview

In **Jframework**, the **Phone Number** is a core identifier for user. The system uses phone numbers to:

* Send and receive **SMS OTPs** for login and phone number verification.
* Allow users to **register a new user** using their phone numbers.
* Serve as a secure method of **identity verification**.

Within a **single brand**, each phone number must be **unique**. This ensures that one phone number can only be associated with a single user in that brand.

### E.164 Format

To maintain global compatibility and consistency, **Jframework** stores phone numbers in the **E.164** format:

* Begins with a **"+"** sign.
* Followed by the **country calling code**.
* Contains no spaces, dashes, or other special characters.

**Examples:**

| Country       | Original Number | E.164 Format |
| ------------- | --------------- | ------------ |
| Vietnam       | 0912345678      | +84912345678 |
| United States | (415) 555-2671  | +14155552671 |

***

### Validation Rules

When creating or updating a phone number in **Jframework**:

1. **Required** — A valid phone number must be provided.
2. **Format** — Must comply with the [E.164 standard](https://en.wikipedia.org/wiki/E.164).
3. **Uniqueness** — Must be unique within the same brand.
4. **Length** — Maximum of 15 digits (excluding the “+” sign).
5. **Characters** — Only `"+"` followed by digits `0-9` are allowed.

**Regex Pattern for E.164 Validation**

```regex
^\+[1-9]\d{1,14}$
```

**Explanation:**

* `^` — Start of string.
* `\+` — Matches the “+” sign.
* `[1-9]` — First digit must be between 1 and 9 (no leading zero).
* `\d{1,14}` — Followed by 1 to 14 digits.
* `$` — End of string.

***

#### Storage Rules

* Stored in the database as a **string** in E.164 format.
* Indexed by brand for **fast uniqueness checks**.
* Normalized before storage to ensure consistent formatting across all entries.