A working mobile network is something most of us take for granted. It’s just supposed to work when we need it, which it mostly does. But there’s a really advanced technique behind what we can see, and it’s actually quite amazing that it works to the extent that it does.
A mobile network is built on three active parts that correlate; the mobile phone you call with, the base station for communication, and a call PBX to connect calls. It wouldn’t work as we know it today if these wouldn’t cooperate.
When you call the mobile phone contacts a base station, and the mobile then communicated the number you wish to call, to the station. The base station then in turn contacts a PBX. The PBX connects the number you call from with the number you want to call, so that you can communicate.
- A mobile networks consists of three parts that cooperate.
- The three parts are; mobile phone, base station, and PBX.
- In your mobile phone you dial the number you want to call.
- The mobile phone contacts the base station with the specific number.
- The base station contacts a PBX with the number you want to reach.
- The PBX connects the number you call from with the number you want to reach.
- If one of them isn’t working, you can’t call.
SIM cards and base stations
The SIM card is what identifies what network the phone wants to connect to, which services are included in the subscription, and which number is connected to the card. The SIM card searches a base station that it has the rights to connect with. If the regular network isn’t available it tries to connect to other networks.
The base station that a mobile phone is connected to is called Base Station Controller, and in short; BSC. These stations exist in different datacenters for different carriers. It can also be a Radio Network Controller that your phone connects to, which in short is RNC. These also work as base stations for mobile networks.
The phone PBX that the base station contacts is called Mobile Switching Center or MSC. These PBC centrals work as a link between the mobile phones when they’re about to connect to each other to call, text, video call, etc. Each mobile phone can be identified with a specific number called IMEI.
Safety and risk
A stolen mobile phone that is reported to the police, will have it’s IMEI number entered into a database called Equipment Identity Register (EIR). Here all stolen phones identities are collected which blocks the phone from whatever base station it tries to connect with, which in turn makes the phone useless.
The carriers for the different mobile networks never intercept themselves. Previously it was common with purpose of improving call quality. Interception is only allowed today if there is suspicion of specific crime. The carriers do however not intercept themselves, it’s turned over to an official agency that by law has the right to handle it.
The future requires more radio frequencies for all mobile network to work hassle free. In best case, the world’s telephony would exist on the same frequency, which means phones would always work anywhere in the world. But until then mobile carriers have to come up with new solutions.Glossary