This number gave me a call. They asked for me by name. I asked who was calling? The person gave their first name. I asked, "From what company?" and they hung up. I called back and got a busy signal.
Well, now you've got an answer as to how unknown pests that call already know who you are. This character was only after a name and bailed when questioned. This is enough to pass along and they've now got a name to go with your number--possibly fetches a better price for parties of telepests. You certainly don't want to bother returning the call, either.