Hang ups and no one on the line!! annoying

She told me that I could win $50,000 plus a new car and many other things.  She asked me to hold the line and someone else would talk to me.  No one ever got on the line.  I purposely held on just to see how they were going to try to scam me.  They apparently hung up.

This call was made to my cell phone.  She also asked if I had a Visa, Discover, Master Card etc. account.  I said I did.  I knew NOT to give my number or even which card I had.  I don't know how she got my cell phone number.

They called me as well and when I pick up they don't hang up until I say something. The first time I did this I heard someone gasp and then they hung up. That is the only sound I have ever heard from them.

This number keeps calling my cell phone over and over again.

just got a call from number and they whomever hung up
tried to do something on Quizno's website yesterday  that was the only place I recently posted my number to get free coupons and now I get this call

no message just calls and when i pick up...hangs up...same i as when i return call

I received a phone call from this number, on my cell what is it.