Base station subsystem — the base stations and their controllers Network and Switching Subsystem — the part of the network most similar to a fixed network, sometimes just called the "core network" GPRS Core Network — the optional part which allows packet-based Internet connections Operations support system OSS — network maintenance Base station subsystem[ edit ] GSM cell site antennas in the Deutsches MuseumMunichGermany GSM is a cellular networkwhich means that cell phones connect to it by searching for cells in the immediate vicinity.
The system proposes two sub-systems. Associated with it is the location registers, namely the home location register HLR and the visitor location register VLR which track the location of mobiles and enable calls to be routed to them.
The NSS portion of the GSM network architecture, often called the core network, tracks the location of callers to enable the delivery of cellular services.
There are a few cryptographic security algorithms that GMS employs, including stream ciphers that encrypt plaintext digits. Researchers published open source software to sniff packets in the GPRS network. It has considered the user authentication using a pre-shared key and challenge-responseand over-the-air encryption.
GSM system overview The table below summarises the main points of the GSM system specification, showing some of the highlight features of technical interest. It was also used to store other information such as "phone book" and other items.
The functional architecture of GSM employing intelligent networking principles, and its ideology, which provides the development of GSM is the first step towards a true personal communication system that enough standardization to ensure compatibility.
A variety of vocoders are available for use, being aimed at different scenarios. There are also several implementations of the concept of an extended cell,  where the cell radius could be double or even more, depending on the antenna system, the type of terrain, and the timing advance.
Half-rate channels use alternate frames in the same timeslot.
Phone locking[ edit ] Sometimes mobile network operators restrict handsets that they sell for exclusive use in their own network.