I was gone but this number showed up on my caller ID.  When I called it back, it said that this number is not in service.....what I have learned from numbers like this when nobody says anything, is that it is a computer calling your number to find out if you are a legitimate number or not so that a telemarketing service can call you.
Whenever you get a call with nobody else on the other end at all, immediately hit your pound key about 4-5 times and immediately hang up.  After a few times, this will confuse that computer into thinking you are another computer and it will remove your number from their system.  I have tried this and it does work if its done every time the calls come in.
I was getting calls like this at least 10 times a day, no exaggeration, and I learned this tip and tried it and within 3 days, I never got another one.