The most common mistakes made by people who receive calls from unknown numbers:

Answering the phone.
Instead of answering, let the call go to voicemail or answering machine.  Legitimate callers will leave a message.

Pressing a number "to be taken off the list"
That works for legitimate telemarketers, but legitimate telemarketers would not have called you in the first place, if you were on the DNC list.  Pressing a number on a call from a telespammer merely confirms you answered the phone.

Returning the call.
At best, returning a scammer's call merely confirms your phone is "live", and your number will be added to a list that will be used by even more scammers.  At worst, the call will cost you additional fees, if it is from a foreign country, such as Jamaica (876 area code).  Also, scammers are now spoofing Caller IDs, so the number you see may not really be the number that called you.  It might belong to an innocent, third party.

Arguing with the caller:
Call center employees have probably heard your argument many times.  They may either continue to try to scam you, or they will hang up ... but will also make sure some other scammer calls your number, later.

Blowing a horn or whistle into the phone:
Will irritate the caller.  The scammer may then add your number as a "spoofed Caller ID", so others think YOU are calling them, and YOU may hear horns or whistles!

Forwarding the call to a government office.
Not too swift.  All that does is tie up a line at the govt office, and record YOUR number as the forwarding number!  Realize that your congress person knows phone scams are a problem, and also knows the FCC and FTC have been assigned the task of upholding the laws concerning this problem.  Instead, you should report the problem via normal channels to the FTC or FCC.

Giving the supposed scammer's phone number to other scammers.
May not be a good idea.  The 1st scammer might have used a spoofed phone number, and, if you give it to other scammers, all you are doing is causing more calls to and problems for an innocent person.

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What you SHOULD do:
If you are disturbed by frequent calls from scammers / spammers. obtain a call blocker app, device, phone, or service.  Google is your friend.  Remember, the Do Not Call list is effective for registered telemarketers, but scammers / spammers ignore that law.