These guys call, if voicemail picks up they leave a blank message for a few seconds BUT if I pick up they ask "Can you here me?" ... If you say "YES" they now have your voice **recorded** which they can use for scams that require verbal confirmation (Would you like to buy our product? ... "YES"). The key is to be careful what words you use so that none of them are "affirmative". When they say "Can you hear me? I like to say "No". ;^)