ChatGPT/Codex Suddenly Requires Phone Verification: Why Chinese Numbers and VoIP Are Rejected, and How to Switch Numbers

When ChatGPT or Codex suddenly prompts for phone verification, it's usually blocked at two points: +86 isn't in OpenAI's supported regions, and VoIP numbers like Google Voice are detected and rejected. This article helps you identify the root cause based on the error, choose between short-term and long-term real mobile numbers, and walk through the correct steps for obtaining and using the number.