OpenAI refuses VoIP and Google Voice, and never lets you change the number

The rule, in OpenAI's words

• OpenAI Help Center, on premium, landline and VoIP numbers

  “We do not support use of landlines, VoIP, Google Voice, or premium numbers at this time.”

  https://help.openai.com/en/articles/8983024-can-i-use-a-premium-number-landline-google-voice-or-other-voip-phone-number

• OpenAI Help Center, on why

  “All of those types of phone numbers are often associated with higher instances of fraud or abuse.”

  https://help.openai.com/en/articles/8983024-can-i-use-a-premium-number-landline-google-voice-or-other-voip-phone-number

On channels it is equally definite: “we only support completing phone verification via mobile phone numbers over an SMS text message. In selected regions, we also support WhatsApp verification” (OpenAI), and “Verification codes can only be sent by SMS or, where available, WhatsApp; they cannot be sent by email or phone call” (OpenAI). There is no voice fallback to fall back to.

This is the one page in this section where line type is not a guess. A mobile line is the stated requirement, and the internet numbers people usually reach for are named and excluded. What makes a number non-VoIP explains how a check like that is actually run, and why a number that looks like a mobile can still fail one.

When OpenAI even asks

Less often than it used to. OpenAI's help page says “Phone verification is no longer required for new OpenAI account creation or ChatGPT usage”, and narrows it to one moment: “Phone verification is now mandated on platform.openai.com for generating your initial API key, though not for any subsequent API key generation after that” (OpenAI).

So for most teams this is a single event in the life of an organisation: the first API key. That is worth knowing before you buy anything, because it means the question is not *which number receives our codes forever* but *whose phone is attached to our organisation's account*.

Three uses, for the life of the number

• OpenAI Help Center, on reusing a number

  “A phone number can only ever be used for phone verification up to 3 times.”

  https://help.openai.com/en/articles/8983031-how-many-times-can-i-use-the-same-phone-number-to-complete-the-phone-verification-associated-with-an-openai-accounts-first-api-key-generation

• OpenAI Help Center, on phone-only signups

  “Even if you only used phone verification once, the phone number is locked from creating any additional accounts in the future.”

  https://help.openai.com/en/articles/10388702-phone-only-signups

OpenAI also warns about numbers with a past: “Recycled or reused phone numbers can lead to this error. Currently, there is no workaround” (OpenAI). A number that somebody else already spent on an OpenAI account cannot be un-spent.

And you cannot change it

• OpenAI Help Center, on changing the number

  “OpenAI does not offer the option to change or update the phone number associated with your account. This is true for ChatGPT and the OpenAI API.”

  https://help.openai.com/en/articles/9135134-how-to-change-the-phone-number-associated-with-your-account

Read that as a commitment, because it is one. Whatever number verifies your organisation's account is the number on that account permanently. If it is an employee's handset, that fact travels with the employee. If it is a line the company holds, it stays with the company. Neither can be undone later.

What the Terms say about sharing

This is the part that decides whether a shared inbox is appropriate at all. OpenAI's Terms of Use state: “You may not share your account credentials or make your account available to anyone else and are responsible for all activities that occur under your account” (OpenAI). A team inbox that shows a one-time code is not a shared credential, and a shared password is. Keep the two apart: the line can be the organisation's, the login stays one person's.

Where a Cleat line fits

One case, and it is a real one: a company generating its first API key that has no phone number of its own. The founders are outside the US, or the account belongs to the business and nobody wants it welded to a personal handset that can never be changed. A Cleat line is a real US mobile number, not VoIP, held by one identity-verified person, at $24.99 a month. For the agent side of this — a number a process can read rather than a person — Cleat for AI agents covers the MCP server and the tool that waits for the next code.

When Cleat is the wrong answer here

• You need a second or third account. The cap is three verifications for the life of a number, and OpenAI says a used number is locked from creating additional accounts. That is the rule working as intended.
• You want to share the login. OpenAI's Terms forbid making the account available to anyone else. Invite people into the organisation instead.
• You already verified on another number. There is nothing to move: OpenAI does not support changing the number on an account.
• You want a code by call or email. OpenAI says codes go by SMS, or WhatsApp where available, and nothing else.

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