Hi:
Is it illeagel to call someone that she doesn't like you?I doubt my
boyfriend cheated on me.So can I just call the girl's number and ask
her what is going on between themselves?Is this a kind of harrasement?

No, it is not illegal to place a phone call to any number accessible
by a normal phone. If you regularly repeat the pattern such that you
cause a disturbance in anyone's life, however, or decrease their
ability to function normally, you can theoretically be charged with
harassment, but probably won't be in a simple case like this unless
you make a nuisance of yourself.

If it's illegal to call someone who doesn't like you, all the
telemarketers would be rotting in jail. ;-)

I doubt very much if a single call would be illegal.  If you get into
the habit of making repeated calls, then there may be a harassment
issue.

I know that girl doesn't like me but only she can tell me the
truth.Actually we had a fight before.I don't know what will she react
if I call her.

Well, either she'll respond or she'll hang up on you. If she hangs up,
don't call back, that would be the beginnings of harassment, and
besides force isn't a good way to get answers anyway.

no but money is