We have an IVR system set up through Ringcentral.

Press one for sales, press 3 for all other inquiries.

When you press 3 the connecting message ends with “It is company policy that we don’t do business with phone solicitors of any kind. If you a re a phone solicitor, please hang up now.”

Robocallers can’t “press one” to connect. Live spammers hear the message and (for the most part) hang up. Even if they don’t hang up, #3 goes directly to a voicemail. The live spammers also don’t want to talk to sales staff, so they don’t bother pressing one.

Additionally, I have Mr Number installed on my personal cell, and it doesn’t ring unless you are a contact. If something is important, they can leave a message.