Weird prank call

Actually I'm having two cell phone.
I really don't need two cell phone, but I have it.
One of the two rarely use it. Few people know that phone number and e-mail address.
Recently only my boyfriend message me to that phone. It's kind of like a dedicated phone line between my boyfriend and me.

Last night, I was awoken by the ringing that cellphone suddenly. I was surprised because the cellphone was a dedicated phone with him. I thought something may have happened to him. I answered the phone in half-asleep way.
Me : Hello?'
Man : Hello?
Me : What's happened?
Man : I can't sleep because I realized I'm totally alone.
Me : ?? What's happened?
Man : I don't know what I should do. I don't know what to do. I really feel lonely and I can't fall asleep alone.
Me : ???

I doubted of him. Because it was totally different voice of my boyfriend. and he totally doesn't say such a weird conversation.

Me : Who are you?
Man : You don't know who I am?
Me : I don't know.
Man : I'm so sad. I'm completely sad because you should know me.

I noticed that it was surely prank call. It was hentai call!!
I hung up the phone. Weird man called again and again!
But I felt really sleepy and I wanted nothing to interfere with my sleep. I didn't answer the phone.

In this morning, I realized the weird man called me over 10 times last night.
It's frightening to me!!
And KIMOI----!!!

I just pray he won't call me anymore!