Asking Telcommunication Help?

[qaisbyte]

My assignment is:
Suppose that we have a company has fifty branches in varry places what is the most ecnomic and most secure connection you suggest to use? Is it telephone lines but it is slow and doesn't accept more than three connections at the same time. so kindly state you suggestions?

[Doogle]

The purpose of the assignment is to measure how much you understand of what you've been taught about Telecommunications. It would be a complete waste of your time in class if you just got suggestions from more experienced people here.

If I were you I'd do some Googling, prepare your answer from the information you gather and apply your knowledge from what you've been taught.

[qaisbyte]

Well, Doogle I am already doing Googling, but I need a keys to rush up on them because I am just a beginner. I was thinking of VPN (Virtual Private Network) is it safe no one can hacks it. And What is firewall exactly do? and how much does it cost?
What the banks use to connect there branches but I think there connections are very expensive?
Please anyone share my thoughts!