When developing, testing, or signing up for modern platforms like OpenAI (ChatGPT), WhatsApp Business, Google, or Telegram, you have likely encountered these frustrating errors:
Why do these errors happen even if you use numbers from popular providers like Google Voice, TextNow, or standard Twilio virtual numbers?
In this post, let's explore how modern authentication systems detect virtual lines and why physical Non-VoIP carrier SIMs are required.
1. How Modern Carrier Lookup & VoIP Detection Works
When you enter a phone number on a modern web platform, the backend verification engine queries a Carrier Lookup API (e.g., Telesign, Twilio Lookup, or Neustar) in real-time before sending the SMS.
