[vbcr]

...and to press #4 to talk to their security department

Does something bad happen by pressing a number on dial pad or they just transfer to a human to talk to. Just curious because I heard from someone that pressing a button was good enough for the spammer who is calling you, but it does not makes sense how that can harm.

[centizen]

It will verify the number/extension called as being a valid target for further attacks. In most situations nothing worse than that would happen.

I have however seen a slightly different breed of attack, where an attacker calls a victim (usually a switchboard attendant) and asks to be transferred to extension 9190. If this happens, they dial the rest of a 1-900 number and rack up charges.

[level]

It's probably used to weed out targets such as the blog author, who know it's a scam already, rather than connecting them to a real person and wasting the attacker's time.