Why do I get calls that ring once before going to voicemail?

Episode 1318 (41:51)

Chris from Florida

Chris also wants to know why a call will ring once and then go directly to voicemail. Leo says that's an odd one and he has this happen too. Is it something the telemarketers have figured out? It could be carrier specific. Chris can sign up with the DoNotCall registry but that won't stop telemarketers from outside the country. Another option is to use Google Voice for everything, then he can program Voice to forward telemarketer calls directly to voicemail or reject them altogether.