From a global perspective, mobile telephony today is synonomous with GSM. Currently GSM and UMTS mobile networks account for about 2.5 billion subscribers, i.e. about a 5/6ths of the world's total population. There are 5 GSM/UMTS subscribers for every subscriber of one of the other mobile bearer technologies.
One of the principle characterstics of GSM is the clean separation of network infrastructure and user equipment. Network infrastructure is provided by local network operators and generally works with any user equipment conforming to the standards. The user equipment is further divided into distinct "mobile equipment" (ME) and "subscriber identity module" (SIM/USIM) domains. The SIM/USIM is a small smartcard that securely stores the network operator's information regarding the subscription and allows secure authentication of the user to the network.
The SIM/USIM is provided by the network operator and can be used in any GSM standard conformant user equipment. User equipment can similarly be used with any network by simply changing the SIM/USIM card. Mobile equipment is designed without regard to any particular network operator and mobile network infrastructure is manufactured and deployed without regard for any particular mobile equipment.
This architectural model fosters the maximum competition among network operators competing on the basis of the quality of their network infrastructure. At the same time there is maximum competition among handset manufacturers competing on the basis of the quality of their handsets.
The freesmartphone.org collaboration takes place primarily in the context of GSM/UMTS user equipment (terminals) and network services. However, many of the services and capabilities resulting from this collaboration may ultimately be suitable for use in mobile telephony environments other than GSM/UMTS, particularly CDMA2000-xxx.
The following standards provide common reference points and vocabulary and are pretty much prerequisite to participating in the freesmartphone.org collaboration:
- TR 121.905 "Vocabulary for 3GPP Specifications" (56 pages)
- TS 123.101 "General UMTS Architecture" (16 pages)
- TS 123.227 "Application and User interaction in the UE; Principles and specific requirements" (15 pages)