Telemarketing time wasters

So I received a call on my cell phone the other day. It went like this:

Me: This is Val.
She: Hi, is this Ghustaive? (the U pronounced as in ‘bus’ and not ‘goose’.)
Me: No, this is Val.
She: Can I speak to Ghustaive?
Me: No, this is not his number.
She: Is this 0839825042?
Me: Yes.
She: And this is not Ghustaive’s number?
Me: No, this is my phone number, that is why I am answering the phone. What is it in connection with?
She: Well if you are not Ghustaive, then you wouldn’t know if I told you.
Me: Well, this is my phone number you dialled so perhaps I am allowed to ask.
She: And you say you are…?
Me: Val.
She: So how can you both have the same number?