GSM PHASES

    In the late 1980s, the groups involved in developing the GSM standard realized that within the given time-frame they could not complete the specifications for the entire range of GSM
services and features as originally planned. Because of this, it was decided that GSM would be released in phases with phase 1 consisting of a limited set of services and features. Each new
phase builds on the services offered by existing phases.

Phase 1

   Phase 1 contains the most common services including:
          • Voice telephony
          • International roaming
          • Basic fax/data services (up to 9.6 kbits/s)
          • Call forwarding
          • Call barring
          • Short Message Service (SMS)
 
Phase 1 also incorporated features such as ciphering and Subscriber Identity Module (SIM) cards. Phase 1 specifications were then closed and cannot be modified.

 
Phase 2

   Additional features were introduced in GSM phase 2 including:
          • Advice of charge
          • Calling line identification
          • Call waiting
          • Call hold
          • Conference calling
          • Closed user groups
          • Additional data communications capabilities

Phase 2+

     The standardization groups have already begun to define the next phase, 2+. The phase 2+ program will cover multiple subscriber numbers and a variety of business oriented features.
Some of the enhancements offered by Phase 2+ include:
         • Multiple service profiles
         • Private numbering plans
         • Access to Centrex services
         • Interworking with GSM 1800, GSM 1900 and the Digital

    Enhanced Cordless Telecommunications (DECT) standard Priorities and time schedules for new features and functions depend primarily on the interest shown by operating companies and manufacturers and technical developments in related areas.