Ways to keep them on the line:
Ask if they can wait just a minute while you take care of something. Come back in a minute and ask they continue to wait as you will be right with them.... do this as long as they will hang on the line. Don't let them say anything and you don't answer any questions. Just keep asking "Please wait just a moment longer and I'll be right with you."  Sometimes I set the phone down in front of the television or radio if it is on. It will give them something to listen to... :)
Tell them you can't understand what they are saying and you need them to repeat EVERYTHING!
Ask them general/personal questions: How's the weather where they are, how is their family doing? Are they diabetic? How are their bowels doing?  I think you get the gist... have fun!

This guy calls me every day. I can't understand him other than he calls me by the wrong last name.

Lol... Love it!

Everyday, we receive at least 10 calls from this number. Everyday, we tell them to remove us from their list. They continue to harass us.

looked up the number before I answered.  I saw all of your comments and didn't answer.  I just blocked the number (thank goodness for iPhones!).  Thanks for the help!