Everything on this page is sold, openly, to people who are told it is a shortcut. It is not a shortcut and it is not a grey area. Each one is a way of attaching a payment history to an identity that did not earn it, which is the definition of the offence.
A "credit privacy number" is presented as a lawful alternative to your SSN. There is no such thing. In practice the numbers sold are either fabricated or belong to someone else — frequently a child or a deceased person — and using one on a credit application is identity theft and loan fraud, on a federal form, in writing.
A real number combined with fabricated details to create a person who does not exist. It is the fastest-growing form of financial fraud in the country, and the customer who buys the file is the one who signs the application.
Paying to be added as an authorized user on a stranger's aged account so their history appears on your file. The history is not yours, the lender is being told it is, and both bureaus and underwriters detect the pattern — the usual outcome is that the account is stripped and the file is flagged.
A dormant entity with an old registration date, sold to make a new business look established. The age is cosmetic; there is no trade history under it. Underwriters look at the tradelines, and using the age to imply operating history is misrepresentation on the application.
PAYDEX is computed from reported, dollar-weighted, on-time trade payments. Nobody can guarantee it, because nobody but your vendors writes to it. A guarantee here is a guarantee that something other than real payment history will be used.
This is general business-credit education, not financial, legal, or tax advice. Confirm specifics with a licensed professional and the official sources directly.