For anti-fraud and abuse reasons, we do not allow you to use your number for phone verification for more than 2 unique OpenAI accounts. This is true only if you create the additional accounts before deleting any account linked to that phone number. After account deletion, we do not allow you to unlink phone numbers, and the 2 unique OpenAI sign ups limit still applies. If you need to create another (3rd) unique OpenAI account then you'd need to use a different number.