Verifying a number with reverse flash-call

Reverse flash-call (reverse_flash_call) is the cheapest way to verify a number. The user makes a short call to the number you show them, and Verificahub confirms it automatically by Caller ID. No code entry needed.

What the user sees

1. In your app the user taps "Verify number".
2. You show them a number to call.
3. The user calls — they can hang up immediately; the call is free for them.
4. The number is verified automatically within a few seconds.

Step 1. Initiate the verification

curl -X POST https://api.verificahub.ru/v1/verify \
  -u api_key:api_secret \
  -H "Content-Type: application/json" \
  -d '{
    "phone_number": "+79991234567",
    "method": "reverse_flash_call",
    "expiry_seconds": 300
  }'

Response 201 Created:

{
  "request_id": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
  "phone_number": "+79991234567",
  "method": "reverse_flash_call",
  "status": "sent",
  "cost": { "amount": 0.25, "currency": "RUB" },
  "expires_at": "2026-06-17T12:35:00Z",
  "number_to_call": "+79090000000",
  "code_length": 4
}

• number_to_call — the number to show the user with a "Call this number" label.
• request_id — the session id you'll use to check status.
• expires_at — when the session stops being valid.

Step 2. Show the number to the user

Display number_to_call and ask them to make the call. The call is short — the user can hang up as soon as it starts dialing.

Step 3. Wait for the result

Poll the session status until it becomes verified (or expired):

curl https://api.verificahub.ru/v1/verify/3fa85f64-5717-4562-b3fc-2c963f66afa6 \
  -u api_key:api_secret

{
  "request_id": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
  "phone_number": "+79991234567",
  "method": "reverse_flash_call",
  "status": "verified",
  "cost": { "amount": 0.25, "currency": "RUB" },
  "created_at": "2026-06-17T12:30:00Z",
  "verified_at": "2026-06-17T12:30:42Z",
  "expires_at": "2026-06-17T12:35:00Z"
}

Once status is verified, the number is confirmed and you can let the user through.

tip

Poll the status every 1–2 seconds. Verification usually arrives within 10–30 seconds of the call.

See also: statuses and errors.