Who called from 6474274905

they have called a total of over 20 times between yesterday and today. the calls JUST started yesterday.  They dont leave a message.  it is VERY annoying!

Keep calling and when i answer i hear silence then a hang up

They calked me, when I answered they asked for someone I didn't know. When I said it was the wrong number, they hung up.

Also got this call. This is the extent of the convo.
Me: Hello?...(3sec pause)...Hello?
Caller: (Breathing out noise) *Hang Up*

Toronto calling address.

Keeps calling everyday for the last week and never leaves a message. I figure if it is important then they would leave a message. Otherwise why keep calling?