Did you have a cramp in your hand that prevented you from hanging up?  

Not to be harsh, but if you spent 15 minutes chatting, it is your own fault.  No need to curse, blow whistles, or whatever, but don't keep talking until they get enough material to splice together a recording that has you agreeing to their pitch.

There is no need to be courteous to someone who invaded the sanctity of your home.

Alex,
Your number may have been unlisted but all cell phone numbers were sold to telemarketing this month. This really sucks!

Have been receiving several calls from this number today. I called the number to have telemarketer's blocked from calling me! So why are they still calling? I think they should have to pay for the call not me, I never invited them to call!!!!

This number is a telemarketer selling oral HGH oral sprays I made the mistake of answering the phone and was stuck for 15 minutes., When I told him that I wasn't going to spend $249 on this he got rude so I hung up on him !

Has called my ph# several times and never leaves message.  I have an unlisted number.  How did they get my phone number?  Getting sick of this number calling me.  How can I stop it?