Some companies and telemarketers may be required by federal law (Federal Trade Commission) or by state law (Public Utilities Commission) to use an independent company to check and confirm with a customer before implementing a change or completing a sale for a new service or product when the transaction is completed by telephone. This is called "third-party verification" or "TPV."
The purpose is to ensure that the purchaser understands and fully agrees to the purchase/change being made to their account. The purchaser is typically asked to confirm their identity and their order. Audio recordings of the confirmation are usually retained as evidence of the confirmation and to protect the seller in the event of disputes at a later time. There are companies that specialize in providing third-party verification services.