If I (or you) receive a call from a number I (or you) do not know, or an E-Mail from an E-Mail address I (or you) do not know do not answer/open it. If it is really important, the caller will leave a message, and who ever sent you the E-Mail will attempt to contact you by other means. I recommend you just block the number or send the E-Mail to your Spam Folder.
Female recorded voice blathered on about how thieves could defeat my home security system by cutting the phone lines, but that the new wifi systems don't have that issue, and then asked three if I wanted a free new home security system. I said nothing each time, hoping to finally get a number I could press to get off their list, but none was offered.
Called three times today. I never pick-up a call that says it is unknown or even if I don't know the person.
I have an idea that it was the person that always calls about my good credit and wants to give me a better deal.