Serves you right. Why did you answer? Especially if you do not recognize the number? NEVER EVER EVER answer the telephone if you dont recognize the number. Thats what you have voice mail for. If people dont leave voice mail then it cant be all that important.
When I called back, it says if you wish to be put on the do not call list, please press one and I did press 1. Then i googled and found this message thread and wonder it did anything to harm when pressed #1 key.