Same happen to me I picked up they hung up I didn't call back I said hello and nothing .. Damn cell phone companies for releasing or numbers it's the reason we get telemarketing calls now..
Got a call today from this number. He asked for me by name and asked if I want to donate to a cause related to breast cancer. I called the number back later and got his voicemail (same voice). He said "press '1' to donate; press '2' to be removed from the call list". I did neither.
I sent the call to voicemail since i did not recognize the number. They didnt leave a message and when i called back got a busy signal. Oh well, not interested, hope they dont bother me again.