by Prithvi Ganesh K



Before we hit the secrets behind the networks, I’d like to  throw light on the very basic things we use and the wonders they do because no matter how much u study about them they seem supernatural  A transducer, well we all know what it does, changes one type of energy to another yeah?..just try thinking how that can be made possible. Converting  voice signals to light and electrical signals! Photoresistors which use light to manipulate  resistance. I believe these are the real wonders of the world. If u think similar ,if such concepts intrigue you, bitstream is just the place for you .Stay tuned to our regular updates. Getting back to where we started….


What really happens when a call is made from one mobile network to another?  Instead of boring infographics, let me try and explain it through the game of football instead….


1.  Imagine a call being initiated, just like a goalie looking to pass the ball to his player.

2.  When the number is dialled, the phone sends the request to the cell tower it’s currently connected to – much like the goalie passing the ball to his defender to take forwards.

3.  The call request is forwarded to the base transceiver station (BTS) from the tower.  This is like Xavi making a pinpoint pass through the midfield to another Barcelona player.

4.  From the BTS, the call is connected to the base station controller (BSC), which allots the call a frequency channel to communicate over.  This is akin to a football team keeping their shape, and making sure they stay in their positions (or their allotted “frequency”).

5.  The call is now switched to a mobile switching center (MSC).  If the call is for another user in the same home network, the steps are retraced to the base station of the other user.  This is like reaching the goal mouth of the opponents’ goal and back passing all the way back to your own goal line.

6.  If the call is for a user on another network (another operator), the call is passed from the MSC to a gateway MSC that switches the call to the appropriate operator’s MSC.  Think of it as losing possession to the other team.

7.  Here’s where football stops making sense in the equation.  Instead of the play turning around, imagine if both teams wanted to attack the same goal…  The call is carried forward from MSC to BSC to BTS and all the way to the base station of the called party’s location.

8.  There’s also a home location register (HLR) that each operator maintains, which knows which phone is where (or latched on to which base station).  Also, an authentication center (AuC) checks whether the subscriber being called has the required authorisation and credentials to receive calls.  So if you haven’t paid your bill or furnished proper documents, the AuC is the one who gives you the red card – like a referee does.

9.  When all goes well, the correct subscriber is connected to and you hear ringing at your end, as the networks finally connect the two phones – it’s like a forward taking a shot at the goal.

10.  The called party hears his phone ring.  Think of them as the opponent’s goalie.  If the call goes unanswered or is rejected, it’s like a goalkeeper’s save, and you start from scratch all over again.

11.  When the call is answered, it’s like a goal being scored ,                                                                                                                                                                                                                                                                                                                   and the celebrations begin with a “Hello!”                                                                                                                                                                                                                      

12.  Of course it usually turns out to be a telemarketer, trying to sell you something you don’t really want or need.  So it’s usually the mobile operator and the marketing companies that celebrate most of the calls that get through!

The next time your calling someone try recollecting this whole process(the soccer game) which occurs in a period of 3 SECONDS  :P!!