called and hung up

This call was placed to my personal cell phone at about 4pm on a Wednesday, May 22nd.  It was a recording regarding a "redemption reward reserved in my name" (yeah right) and it was for a gift card from either walmart or sams or some other store.  I was to press 1 for the gift card or 2 to be removed from the call list.  I pressed 2.

Hangs up.  Does not leave message.  Suspect it's a telemarketer.

Didn't answer...like to know how these people are getting my number though...2nd number like this calling me in the last few days

They do not need to know your number to call you, just an automatic dialer that calls each number in a given area code and exchange in sequence and passes any live answers to an agent.  Only if they know your name have they obtained contact information from somewhere and with reverse Caller ID even that is not necessary if you actually answer the call.