Event - British Telecom Roullette

Well, the random number pressing started when I had a phone number, but it wasn't the number I was calling about, and I didn't know it. Do I press *, or nothing, or what?

BT: Our records show there is a phone line in that house.
CD: Hmmm. Probably the previous tenent, or possibly the landlord has it for some reason. Can you give me the name it's under?
BT: I'm afraid not. We can confirm if you know it.
CD: *scrabbles through christmas cards*
CD: [Previous tenant]
BT: No.
CD: [Last-but-one-tenant]
BT: No.
CD: [Landlord]
BT: No.
CD: Animal, vegetable or mineral. What's the first letter?
BT: Why don't you call the ladlord?
CD: Wait, is it "Cambridge Residential"?
BT: *click*

NB: Guess which line I started making up the conversation at.