Dealing with companies can be frustrating, because they like to appear opaque to the outside world. When you look on the website you find a page with contact information. You'll find a phone number and an email address, and maybe more than one if it's a large company with several departments. But they all point to the reception. Few companies are generous enough to give you direct access to their personnel with a listing of employees and their contact information.

So if there is a person you have to get to you have to do it through the reception. "Yes, I am blah and I need bleh and why don't you just transfer me to the person I need to talk to, per favore!" It's not a lot of fun, but this way whoever makes this decision to give out only the number of the reception can also decide who may and may not receive calls. And even on what conditions. If you say the magic word then, yes, you can get Frank on the line, otherwise not. And maybe Steve has been known to say too much and has a history of divulging information he wasn't supposed to. So no, you can't talk to Steve.

Well, this is the principle of a firewall. The reception screens calls with the discretion to reject or divert according to the protocol that has been instituted. Some people can be reached anytime, others only at certain intervals. Some are available depending on your request, and some are completely unreachable.

This picture, however, conflicts with the original meaning of the word firewall, which is a wall erected to stop a fire from spreading. Unconditionally.