Silent Authentication

Silent Authentication uses a mobile phone's Subscriber Identity Module (SIM) to verify a user's identity, without any user input. It checks the user's phone number against their carrier's records to confirm that it is active and legitimate.

Once a request is verified, you can continuously authenticate the user until the request either expires or is canceled by the user.

Advantages

• Minimal user input - Silent Authentication is very user friendly; once the user has entered their credentials, the authentication process happens in the background. There are no OTP codes to input, making the process as frictionless as possible.
• No phishing - By moving authentication directly between the carrier and the mobile device, the threat of phishing via SMS is removed.

Requirements

• The user must own a mobile device - Silent Authentication needs the user to authenticate from a mobile device.
• A cellular network connection is required - Silent Authentication relies on a verified GSM response from the device to prove its credentials, which is not sent if the user is connected to Wi-Fi. The user must therefore trigger the authentication request using cellular data. You can use our mobile libraries to help force a mobile connection.

Bypass WiFi for Silent Authentication

Vonage provides two Libraries that you can use in your applications to help you make a HTTP request over a cellular network, even when on WiFi. These are available through GitHub:

• Android
• iOS

Click on each platform for more details, including installation instructions, compatibility information, and usage examples.

Implementation

Silent Authentication can work both synchronously and asynchronously (using webhooks).

Coverage Check

Verify Silent Authentication supports both synchronous and asynchronous coverage validation mechanisms, controlled by the coverage_check parameter.

Synchronous Validation (default)

coverage_check=true follows a synchronous flow and triggers a real-time network coverage lookup:

• If the destination network is supported, Verify also verifies that your Vonage Application is correctly configured with Silent Authentication enabled.
• If all checks pass, the API returns a check_url.
• If the destination network is unsupported, the API returns an immediate error. This prevents unnecessary redirection flows.
• If the network is technically covered but your Network Application Profile has not been approved by the operator, the request is rejected synchronously with a 412 error. To improve carrier integrations and reduce failed authentication attempts, Network registration is becoming mandatory for live Silent Authentication requests.

Asynchronous Validation

With coverage_check=false, Verify follows an asynchronous flow:

• The API always returns a check_url. It allows you to manage network validation on your side.
• If Silent Authentication is the only channel and the network is unsupported, the request will fail with an error.
• If a failover channel is configured, Verify can automatically fall back to the next channel.
• If a Network Application Profile has not been approved, the error is delivered asynchronously via callback. To improve carrier integrations and reduce failed authentication attempts, Network registration is becoming mandatory for live Silent Authentication requests.

Failover Behavior and Error Visibility

If a failover channel is configured, Verify returns a successful response to the initial API request (including a request_id) regardless of Communication Service Provider (CSP) support or Network Registry status. If Silent Authentication later fails, Verify switches to the next channel and notifies you via callback. Because the initial response is successful, you cannot determine the exact failure reason from that response (for example, whether there was no coverage or the CSP was not supported). If callbacks are not implemented, the unsupported network condition will surface during the initial redirection attempt.

For additional information, refer to the Verify API Reference.

Environments

Production

Using Verify in production requires the registration of your application using the Network Registry. Vonage’s Network Feature Registration service automates the registration process through a common dashboard interface and sends the information to the operators for approval.

Non-Production

Access to non-production environments is provided through the Network Registry Playground, which supports all countries where Silent Authentication is available. For the complete list of supported countries, see Availability.

Using Silent Authentication in Germany

When using the Silent Authentication in Germany, you must include specific wording in your application to gain the user's consent before any IP matching / processing:

English

German

Availability

Silent Authentication is currently available in the territories listed in the table.