I am getting calls from this number every single day I don't know who is this stupid idiot when I answer he hang up

We received 5 calls (3 calls yesterday and 2 calls today) from (613) 688-2311. He also knows my son's name somehow. Did he know any of your names? He hangs up when asked the purpose of his call. When I tried to call back to the number, the system is busy most of the time and the system says "let bell notify you when the line is free within next 30 minutes, press star; $1.50 applies"

I get this number when a friend is using a long distance savings calling card, the number is the calling cards local (Ottawa) number it sends calls through. He usually calls when he is on the road between Toronto and Montreal.

Just got a call from this number. 613 being my local area code i took the call and no one was on the other end ready to talk.
I am on Rogers Wireless in Ottawa.

I get calls from this number every day and when I answer, nobody replies.  Getting extremely annoying so I screened them out, whoever they are.  Can't be that important, otherwise they would talk to me.