Test numbers are special phone numbers you register on your account that never reach a real carrier. When you create a verification against a test number, Prelude short-circuits the flow: no message is sent, no cost is incurred, and the code is a fixed value you set when creating the number. Reach for them in automated integration tests and during local development, any time you want to exercise the end-to-end Verify flow without touching production messaging. Test numbers let you simulate:

• Successful verification flows
• Anti-fraud outcomes: challenged, blocked and shadow_blocked, with each blocking reason
• Silent Verification, both the silent success and the fallback to a message
• Errors due to invalid codes, expired verifications or too many attempts

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Responses

Each test number carries a response that decides what the API answers for a verification against it. The default, valid, is the successful flow above. The other responses let you exercise every branch of your integration, including the ones that are hard to reach with a real number: <reason> is one of suspicious, repeated_attempts, invalid_phone_line, invalid_phone_number, in_block_list, invalid_signature and expired_signature, exactly as the Create verification response reports it. blocked_<reason> and expired never check a code, so those numbers need no attempt code. A test number can also carry a short description, shown under the number on the dashboard.

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Silent Verification

The silent_verified and silent_mismatch responses simulate Silent Verification without any carrier involved. A verification created against such a number returns "method": "silent" with a request_url, exactly as a real eligible number would. The SDK follows that URL and receives either the attempt code or a failure. A test number on any other response is never offered the silent method, which lets you test the fallback branch too.

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How to use test numbers

To create a test number, go to Verify API > Configure > Numbers on the Dashboard and click Add Number in the Sandboxed Numbers section. Then fill in:

• Phone Number: the E.164 number to sandbox.
• API Response: one of the responses above. Defaults to valid.
• Attempt Code: the only code the Check endpoint accepts for this number, 4 to 8 characters. Not asked for blocked_<reason> and expired, which never check a code.
• Description: optional, at most 80 characters, shown under the number in the list.

You can also manage test numbers through the management API, which takes the same response and description fields.