Contact your phone company about caller ID services. With caller ID, you'll be able to see who is calling before you answer, then block your number from callers who won't allow you to identify them.
Resist trying to reason with a telemarketer. Telemarketing companies have scripted responses for almost anything you say.
Prepare for those unwanted calls before they happen. Write the phrase, 'Put my number on your don't-call list' on a memo by your phone.
Stay on the line when a telemarketer calls. You actually have to speak to telemarketers in order to get them to stop calling you.
Announce your prepared phrase, 'Put my number on your don't-call list,' to the telemarketer. Per FCC requirements, once you've said this sentence, the telemarketer is prohibited from calling you again for 10 years. (Make sure you say that exact sentence. Just saying 'Take me off your list' or 'Stop calling me' does not legally force the telemarketer to stop calling you.)
Write a letter to Telephone Preference Service, Direct Marketing Association at P.O. Box 9014, Farmingdale, NY 11735-9014. Provide your name, address and home telephone number and say that you do not want calls from any telemarketers. Be sure to sign the letter and keep a copy.