Internet for beginners All about Internet in the Philippines



What's behind that modem?
By Andy Liao (

Ever wondered how you are able to talk with a friend who is continents away? Or how is it that you are able to do a lot of things and go to a lot of places by just being on the Internet? Ever asked your self what made all these possible? The answer may just be sitting there on your computer or it may be housed inside your computer's casing: your modem.

Every time you try to get on the Internet, your modem does the talking and communicating. You'll hear a series of beeps and weird gurgling sounds and then a few seconds later, you're connected to the Internet.

So, how exactly does your modem talk?

If you notice, your phone set or modem is connected to a small box known as a D-box. The 'D' stands for demarcation, and this separates your internal communication wiring from the outside line. Now outside your house you'll see another box called the subscriber box or station protector. This serves as a protection to your premise equipment such as phone or modem in case lightning strikes your phone line.

Going further you'll see another box. This time it's mounted on an electric or telephone pole. This box is called a pole terminal or sometimes a DP (distribution point). Looking further to your street, there's another big telecom box. This time, this one is called the DLC (Digital Loop Carrier). Inside this box, your modem call is converted from an electrical signal into pulses of light wave.

The communication link that comes out of this street box is the fiber optic cable. This cable sometimes runs underground or is laid up high over telephone poles. At the end of the cable, there's a new box that can be found inside the telephone exchange. Inside the building, they connect your modem call to a new box that combines all modem calls into a big chunk of data. This data is now fed again to another box which converts the data into streams of light which is fed to another fiber optic cable (submarine cable) but this time, it runs for thousands of kilometers under the ocean. At the end of this cable, the fiber optic cable is connected to another telephone exchange that's in another country. This will now convert the streams of light back into an electrical signal that are then again fed to the street box. The signal will end up in a foreign ISP equipment that runs its web server and finally your friend's ISP connects his modem call the way you connect to our local ISP.

So the next time you wonder how your modem is able to make you and your friend communicate despite the distance, just remember our cable and box story.


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