On 21/03/2019 16:43, Steve Walker wrote:
On 21/03/2019 16:10, Scott wrote:

[snip]

Except they are not really opt-outs at all.Â* They are a method of
checking the number is valid thus increasing its value when sold on.

They know it is a valid number simply because the line has rung, they
don't even need someone to answer, never mind press a button, to prove
its validity.

It does however mean that they know that the number is one where the
call likely to be picked up by a human. This might increase its value
when sold on.