Overall, the network element in the architecture of a GSM network can be divided into:
1. The Mobile Station (MS)
2. Base Station Sub-system (BSS)
3. Network Sub-system (NSS),
4. Operation and Support System (OSS)
Taken together, the entire network element above would establish a PLMN (Public Land Mobile Network).
MS Mobile Station or a device used by subscribers for talks. Consisting of:
* Mobile Equipment (ME) or a handset, a GSM device which is on the users or customers that serves as a terminal transceiver (transmitter and receiver) to communicate with other GSM devices.
* Subscriber Identity Module (SIM) or the SIM Card, a card that contains all customer information and some information services. ME will not be used without a SIM inside it, except for emergency calls. Data stored in the SIM in general, are:
1. IMMSI (International Mobile Subscriber Identity), is the numbering of the customer.
2. MSISDN (Mobile Subscriber ISDN), the number being the number of customer calls.
Or BSS Base Station System, consisting of:
* Base Transceiver Station BTS, GSM devices that are directly related to MS and functions as sending and receiving signals.
* BSC Base Station Controller, the device that controls base stations BTS working beneath it, and as a liaison BTS and MSC
Network Sub System or NSS, consisting of:
* Mobile Switching Center or MSC, is a central element network in a GSM network. MSC as the core of mobile networks, which serve to interconnect MSC talks relationships, both between cellular and wired networks PSTN, or with a data network.
* Home Location Register or HLR, which serves as a database to store all data and information about customers that is stored permanently.
* Visitor Location Register or VLR, which serves to store data and customer information.
* Authentication Center or AUC, which is required to store all the data needed to examine keabsahaan customers. So the talks are not legitimate customers is inevitable.
* Registration or EIR Equipment Identity, which includes customer data.
Operation and Support System or OSS, is a sub system of the GSM network that serves as a central control, including fault management, configuration management, performance management, and inventory management.
Source : http://id.wikipedia.org/wiki/GSM#Keunggulan_GSM_sebagai_Teknologi_Generasi_Kedua_.282G.29