Codex Asks for SMS Verification on Open? Don't Just Switch Numbers—Handle It in This Order

When ChatGPT web or the Codex client suddenly prompts for phone verification, it's usually a triggered account-level security check, not a bug. This article explains common triggers, OpenAI's restrictions on number types (VoIP and landlines rejected, max 3 accounts per number, no self-service rebinding), and the complete handling order from stopping to investigate to switching to a real carrier number you can keep long-term.