Possible Clues:

• Words after knocking at a friend's door
• 'Hey, don't you recognize this voice?!'
• Front-door response
• Words upon arrival
• Homecoming announcement
• 'Hello ___' (Todd Rundgren hit)
• 'Open the door, dude ...'
• Announcement at the door
• ''Hello ___'' (Rundgren tune)
• Phone ID?