Silent Authentication Updates in Verify API

We’re introducing important enhancements to Silent Authentication in the Verify API. These updates are designed to improve the developer and testing experience and give you more control over authentication flows.

Here’s everything you need to know, and what actions to take before May 1, 2026.

New coverage_check Parameter 

One of the most common challenges with Silent Authentication is handling unsupported networks efficiently. Previously, coverage validation often happened later in the flow, potentially causing unnecessary redirections. 

We’ve listened to your feedback, and we’re improving that. We’re adding a new coverage_check boolean parameter to the Verify API. 

How It Works

coverage_check=true (default)

• Synchronous validation

• If the network is supported, the API verifies that the Vonage Application is correctly configured with Silent Authentication enabled

• If all checks pass, the check_url is returned

• Returns an immediate error if the network is unsupported

• Prevents unnecessary redirection flows

coverage_check=false 

• Asynchronous behavior

• Always returns a check_url

• Allows you to manage network validation on your side

Important Notes

• If silent_auth is the only channel, an unsupported network returns an error.

• If a failover channel is configured, the request automatically falls back to the next channel.

Network Registration Required for Production

To improve carrier integrations and reduce failed authentication attempts, network registration is becoming mandatory for live Silent Authentication requests.

How To Configure It

You must complete the Network Registry process. 

The assistant will help you to create the Business and Application Profiles. Your Application Profile must have a Network Application Profile in “Accepted” status (approved by the mobile operators) and be linked to your Vonage Application in the Developer Dashboard.

You can complete these steps in your Vonage Developer Dashboard:

1. Open the Dashboard

2. Go to Network Registry from the left-hand menu

3. Complete the registration process

4. Enable the Network Registry capability in your Vonage Applications settings

Once completed, your application will be properly configured for live Silent Authentication traffic.

Then, what happens after May 1? 

If a request is made and the Network Application Profile has not been approved by the mobile operators yet, an error will be returned:

• When coverage_check=true, the request is rejected synchronously with a 412 error.

• When coverage_check=false, the error is returned asynchronously via callback.

Deprecation of the sandbox Parameter

We’re also modernizing how you test Silent Authentication. 

The sandbox parameter is being retired. Going forward, testing should be done via the Network Registry Playground, which provides live traffic in a safe and controlled environment.

The Playground offers a significantly improved developer experience:

• Live traffic for supported APIs and countries up to 5 registered phone numbers. 

• Virtual operator support for testing the API in those countries where an API is not yet available.

Rather than relying on a request flag, you now have a more realistic and powerful testing environment.

Migrating to the new Playground has never been easier:

• Remove the sandbox parameter from your Verify API integration.

• Follow the steps described in the Network Registry Playground guide to enable the testing environment in your Vonage Application. Don’t forget to create a new dedicated Application for Playground usage. A single Vonage Application cannot support both Playground and production traffic.

What happens after May 1? The API will behave as follows:

• Requests with sandbox=true will return a 422 error Invalid params. 

• Requests with sandbox=false (or no sandbox parameter) will continue to work normally (parameter ignored).

Action Checklist

Here’s what you need to do before May 1, 2026:

For coverage_check

• Review your current integration

• Decide between synchronous (true) or asynchronous (false) behavior

• Update your API calls accordingly

For Network Registration

• Confirm your Network Application Profile is properly linked

For Sandbox Deprecation

• Stop using sandbox=true

• Migrate testing to the Network Registry Playground

• Ensure production workflows do not rely on the sandbox parameter

Key Date: May 1, 2026

On this date:

• coverage_check becomes available (default: true)

• Network registration becomes mandatory for live traffic

• sandbox=true will return a 422 error. Use the Network Registry Playground instead

Conclusion

Silent Authentication continues to evolve, becoming more reliable, more predictable, and easier to operate at scale. These updates reflect three key goals:

• Improve Developer Experience. The coverage_check parameter reduces unnecessary redirections and provides immediate feedback on unsupported networks.

• Better Network coverage management. Mandatory registration ensures better carrier integrations and fewer authentication failures.

• Better Testing. Replacing sandbox with the Network Registry Playground gives you a more realistic, robust testing environment.