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.
Claude Phone Verification Code Not Received: Handle Four Cases Based on the Error
If Claude's phone verification code doesn't arrive, first check which type of prompt appears on screen: silent non-delivery, send rejected, number already in use, or ineligible number type—each requires a completely different response. This article gives the troubleshooting order, how to judge cooldown waits, and what kind of number to choose when switching so you won't get stuck in the next security recheck.
Which Country's Phone Number Should You Use for OpenAI Registration? Supported Countries, Number Types, and Verification Timing
OpenAI standard registration no longer requires mandatory phone verification, but verification is still needed when creating the first API key on the API platform, triggering security risk controls, or logging into certain clients. You must use a real mobile number from an officially supported country (such as the US, UK, Japan, etc.). Mainland China, Hong Kong, Russia numbers, and VoIP virtual numbers like Google Voice are strictly prohibited. A single number can be used for API verification on at most 3 accounts.
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.
Google says 'This phone number cannot be used for verification'? Distinguish the cause before changing numbers
A practical guide to diagnosing and resolving Google's 'This phone number cannot be used for verification' error by categorizing root causes and offering a systematic troubleshooting sequence.
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