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 defined the next phase, 2+. This program covers 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.

Phase 2++ This phase includes sophisticated enhancements to the radio interface including:

·         Enhanced Datarates for Global Evolution (EDGE), a new modulation method which increases capacity on the air interface.

·         Customized Application for Mobile Enhanced Logic (CAMEL), a standard, governing IN service access while roaming internationally.

·         High Speed Circuit Switched Data (HSCSD), a method of delivering higher data rates per subscriber by allocating an increased number of time-slots per call.