Tell them you're under house arrest and ask if they could bring you a case of beer and some chips.

After they have introduced themselves cry out in surprise and ask them how they have been. This will set them back a few moments while they try to figure out where you know each other from.

Ask them to speak very slowly as you are busy writing down every word they say.

Tell the telemarketer that you are busy at the moment but if they'll leave you their home phone number you'll call them back.