Phone Verification Overview
Introduction to CloudVNO's Verify API for OTP-based phone verification, fraud detection, and number intelligence.
What is the Verify API?
The Verify API provides a complete solution for phone number verification. Send a one-time passcode (OTP) via SMS, voice call, or WhatsApp — then verify the code your user enters.
Built-in fraud protection automatically blocks:
- Disposable / virtual numbers
- High-risk phone numbers
- Known fraudulent number ranges
Verification Flow
1. Your server → POST /v1/verify/send { to, channel }
CloudVNO → sends OTP to user's phone
2. User enters code → Your frontend sends to your server
3. Your server → POST /v1/verify/check { to, code }
CloudVNO → returns { valid: true/false }
Channels
| Channel | Delivery Method | Typical Delivery Time |
|---|---|---|
sms | Text message | < 3 seconds |
voice | Automated phone call | 5–10 seconds |
whatsapp | WhatsApp message | < 3 seconds |
Use sms as the default. Offer voice as a fallback for users who can't receive SMS.
Code Configuration
- Length: 4–8 digits (default: 6)
- Expiry: 60 seconds to 1 hour (default: 10 minutes)
- Max attempts: 1–10 (default: 5)
- Custom template: "Your [App] code is . Do not share it."
Fraud Protection
The Verify API automatically scores each verification request for fraud risk. High-risk requests are blocked before a code is sent, protecting you from:
- SMS pumping fraud (attackers generating traffic to premium numbers)
- Account takeover attempts
- Bulk verification abuse
Review fraud scores in your dashboard.