Same here, with the first call on 1/12/15.
On 1/13/15, I received a call from the same number - asking for a person I know but who has nothing to do with my number.
I got 4 calls from this person and they would always leave a voicemail but didn't say anything on it. I also tried calling the number and I got a busy signal
Just got 4 or more calls. I picked up the last two but they hang up. I tried calling but get a busy signal. I'm going to block the number. so weird...smh.