Got calls from this number twice in one day.  Answered and there was no answer on other end...then hangs up.

Same here, got a call from this number twice this afternoon. Picked up but there was no answer. I called back and got the message "the subscriber you are trying to reach is not in service".

Also had this phone call a few times to my work line. It shows up as "International Gateway" for Caller ID. The voicemail that was left happened to be from a customer in Ontario.

Usually calls from Canada come up without appearing like this, but there may be an alternative number that Canadians use so they're not charged for calls to the US. That's my theory anyway.

Picked up I heard a ring at the other end then a hang up. The second call I ignored.

Somebody called once by the evening but i didn't pick up. Then, looking for information about 612 area code on internet (because I was figuring out who tried to call me) I got surprised because the first website I saw at google's search was this one here, where people are discussing exactly about that phone number!