Most organizations have the ability to control the text block appended as a footer to all external email conversations. This is either called a Legal Disclaimer or Confidentiality Notice. You may have seen such a section starting with: "This message, including any attachments, may contain confidential, proprietary, privileged and/or private information.If you are not the intended recipient, you are hereby notified that any use, dissemination, copying, or storage of this message or its attachments is strictly prohibited."
Your legal counsel may want to add the following sentence to the disclaimer: "All calls will be recorded for record-keeping, quality assurance, and training purposes."