In message om, Dave
Liquorice writes

If you make a sound when you pick up the call, then the calling centre
routes the call to a human who you really don't want to talk to.

I don't think that happens. Silent calls are just the call centre kit
dialing calls before there is an operator free to take the call the
moment it is answered (if it is). Having a CCO not talking to someone
costs money.

Which is why I always tell them to wait a minute while I go and get the
householder

.... and see how long it takes for them to drop the line

--
geoff