# Phone-based authentication

### 📱 Phone-Based Authentication

This section describes the configuration and behavior of **phone authentication**, which enables users to authenticate via **SMS** or **voice calls** using one-time passcodes (OTP).

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#### ✅ Supported Methods

* **SMS**: A one-time code is sent via text message to the user's phone.
* **Voice**: A one-time code is delivered via an automated voice call that reads the code aloud.

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#### 🌍 Global Availability

* **All countries are supported.**
* **Per-country restrictions are not currently configurable.**

> 📌 *Make sure your SMS/voice provider has global routing and supports compliance (e.g., local regulations, sender ID requirements, etc.) for the countries you serve.*

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#### ⚙️ Configuration

| Feature                  | Description                                          |
| ------------------------ | ---------------------------------------------------- |
| **Delivery Channels**    | `sms` or `voice`                                     |
| **From number**          | A e164+ number                                       |
| **From name (optional)** | A human identifier for the number, sometime accepted |
| **Digits**               | **6 or 8**                                           |
| **Template**             | code: %otp%                                          |
| **Integration Provider** | Configured Twilio Account                            |
| **Expiry time**          | 60, 120 and 300 seconds                              |

***

#### ⚠️ Security Notes

* Note: SMS and voice OTPs are **vulnerable to SIM swap attacks** and should not be the sole factor


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