Wrong number fun

So the Angry Phone rings a little while ago (+61424 05 68 65 for those who want to try it) and the following conversation takes place:
ME: Hello?
CALLER: Shamir? (or something similar)
M: No, this isn't Shamir.
C: Shamir?
M: No, you've called the wrong number. This isn't Shamir.
C: Oh... (mutter, mutter) Wrong number... (mutter, mutter - eventually they hang up.)
Disappointment set in for me at this point. I've had some really enjoyable conversations with people that were previously unknown to me on the angry phone. Actually, the most common scenario that plays out is silence on the other end. I have found out from a few people that they never expected me to actually answer. I don't always but if I have the phone on and it's convenient I'll answer.
When I get the silent responses I usually make a couple of attempts to get the person to talk, saying things like "It's really me, not voice mail. It's OK, you're allowed to talk - that's why I gave the number out." Then they hang up without saying anything. It seems I'm too scary for some people to talk to, which I don't understand. Maybe I'm not the best judge.
Anyway, my disappointment was short lived because I got another call a minute later:
CALLER: Shamir?
ME: No, you clearly have the wrong number for Shamir. This isn't his phone.
C: Mutter, mutter, mutter (eventually they hang up again.)
Then, after a much smaller gap, the phone rings again. I didn't make a note of the caller's number before but the number showing up on caller ID looks suspiciously familiar.
ME: Hello?
CALLER: Shamir?
M: Why is it so hard for you to accept you have the wrong number for Shamir?
C: (It sounds like they're having a conversation with someone next to them, I can make out a few words.) Shamir... wrong number... you call... (Then they talk directly to me again) Is Shamir?
M: It isn't Shamir and it's never going to be Shamir no matter how many times you call! (after a little silence they hang up.)
I thought maybe this might finally send them on their way but about 30 seconds later they called again.
ME: Hello?
CALLER: Shamir?
M: Yes this is Shamir.
C: (after a pause) Speak to Shamir?
M: This is Shamir speaking now. What do you want?
C: Who is this? (they sound dubious)
M: This is Shamir. Why don't you believe me? You didn't believe me when I said I wasn't Shamir, now you don't believe me when I say I am Shamir. Make up your mind!
C: Is Shamir there?
M: OK, you got me, I'm not Shamir but he is here. He refuses to talk to you because he says he hates you. He also says he's going to punch you in the face next time he sees you. Now piss off and stop calling this bloody number!
They haven't called back since.