1. Politely Decline: The simplest and most effective way to deal with telemarketers is to politely decline their offer. You can say, "Thank you for your call, but I'm not interested."

2. Ask to Be Removed: Most telemarketing calls are obligated to provide an option to be removed from their call list. Politely ask to be removed, and they should comply.

3. Register for Do Not Call Lists: In many countries, you can register your phone number on a "Do Not Call" list, which should reduce the number of telemarketing calls you receive.

4. Screen Calls: Use your phone's caller ID or a call-screening service to identify incoming calls. You can choose to answer only calls from known contacts.

5. Use Call-Blocking Apps: Consider using call-blocking apps or services that can automatically block known telemarketing numbers.

6. Maintain Your Privacy: Be cautious about sharing your phone number online, especially on websites or forms that may sell your information to telemarketers.

7. Answer and Politely Hang Up: If you answer a call and realize it's a telemarketer, you can politely say you're not interested and hang up.

8. Don't Engage in Long Conversations: Telemarketers are trained to keep you on the line, so it's best not to engage in lengthy conversations. Politely but firmly decline and end the call.

9. Avoid Pranks or Harassment: Avoid using pranks, rude language, or any form of harassment. It's not productive and could lead to legal issues.

10. Complain to Relevant Authorities: If you receive unsolicited telemarketing calls despite being on a "Do Not Call" list, you can file a complaint with your local regulatory agency responsible for such calls.

Remember that telemarketers are just doing their jobs, and many of them understand that not everyone will be interested in their offers. Being polite and respectful in your interactions is a more effective and considerate approach to handling telemarketing calls.