During the summer, I started to receive an inordinate number of telephone calls to the shop phone. These calls were "phishing" and spam calls, mostly to sell things I didn't ask for, nor need. Verizon tells me they come from computer telephone spammers, and nothing can be done about them. When I attempted to call the number back, the automated response was clear, "that number is no longer in service, or has been disconnected". One day, I got over 50 calls from spammers here in Nevada.
So, the answer is to not even answer the calls, but, that means to not answer calls from those legitimately seeking my conversion services. So, I will ask those that are calling from either the 702 or 775 area codes, please leave a voice mail, and I will get back to you ASAP. Thank you for your understanding.
UPDATE, NOVEMBER 6, 2018: The spam, spoof, and Phising calls went off the deep end yesterday, with no hope of stopping them, 71 all day. another 27 from midnight to now, 10:03AM. Another one right now as I write this. These are confirmed to be calls generated from a "dead phone number", from a computer. I am not answering them. It has forced me to answer calls very differently.
What I will ask now, is not only of Nevada callers, but EVERYONE, is to call, and LEAVE A VOICE MAIL. This way I will be able to see if it is a robocall, or if a human being is calling. If you have caller ID that clearly identifies yourself, and I am close to the phone, I will answer with no problems. Also, in your voicemail, please leave name, phone number, email address and time you called. If you prefer, either a text message or email will signify you are not a spammer, spoofer, nor phishing.
I dislike doing things this way, but there is no other choice now, and no fix, except to not answer the calls. Thank you for your understanding.