See the User Guide on page 170 of the PDF:
Send a fax with confirmation
You can set the product so that it prompts you to enter the fax number a second time to confirm that you
are sending the fax to the correct number.
1. From the Home screen, touch the Setup button.
2. Touch the Fax Setup menu.
3. Touch the Advanced Fax Setup menu.
4. Scroll to and touch the Fax Confirmation menu, and then touch the On button.
5. Send the fax.
Normally the option to configure a confirmation page and image is provided by the Fax Setup Utility. Generic steps are as follows:
1. Touch the Setup Menu on the Control Panel
2. Navigate to Fax Setup
3. Select Fax Setup Utility
4. Work through the options and complete the wizard