[mariuolo]

I've been mulling over an idea for some time: set up an answering machine on freepbx with an IVR that requires the caller to push a button before it's forwarded to a (ringing) phone, otherwise sayonara.

That should cut off most robocallers, shouldn't it?

[mlrtime]

Google Voice does this. It makes a human press a number to be connected.

I get almost 0 spam calls on my GV number, but my carrier number is garbage. I swear they sell my ph# to spam orgs on registering.

[bluGill]

Only if so few people use it that spammers don't bother to target beaking the scheme.