I don't like using reference questions where I don't actually help the patron, but this one was kind of funny.
Here at my library in Massachusetts, the phone rings...
Me: Reference Desk, can I help you?
Patron: Hello, this is Margery. I live in Westminster, Maryland, and I'm hoping you can help me with something.
Me: Okay, I can try.
Patron: I used to be pretty friendly with some people that live in Chelmsford, but I've lost their telephone number. Their name is D_____.
Me: Sure, let me check the phone book…
[looks in phone books]
No, I'm sorry, I don't see them listed. Sometimes people have unlisted numbers or cell phones, which means they won't be in the phone book, so I'll check a couple other resources, too...
[looks in List of Town Residents and Property Tax Assessments by Owner]
No, this family isn't showing up as living in or owning property in town. Is it possible they could have moved recently?
Patron: Well, I suppose that's possible. It's been about twenty-five years since I last spoke with them.
Did they by chance give you their forwarding address?
Unfortunately, very few people who move think to leave their forwarding address with the library. The post office does keep this information, but does not provide it to the public.
The patron decided that she was going to have another look around for the number, and then maybe call some mutual friends that might be more in touch with them.