Possible Clues:

• "This is only a test" gp.
• 'This is only a test' gp.
• 'Charlotte's Web' author White and namesakes
• 'This is a test. For the next 60 seconds ...' org
• "This is only a test" grp.
• 'This is only a test' grp.
• Old FCC warning service
• "This is only a test" org.