GSM and 3GPP Specification Numbering Schemes
The GSM and 3GPP specification numbering scheme can be confusing at first glance. According to http://www.3gpp.org/3G_Specs/spec_series.htm, the scheme goes like this:
GSM was divided into releases as follows: Phase1, Phase 2, Phase 2+ (Release 1996), Phase 2+ (Release 1997), Phase 2+ (Release 1998), and Phase 2+ (Release 1999). These were organized into a series numbered 1 to 13, and within each series, specifications were numbered from 00 to 99.
Starting in release 1999, the number 20 was added to the series number and an extra digit was added to the specification number. For example, "03.39" became "23.039." This is where it can get confusing. Where different functionality was required for 2G and 3G systems, 100 was added to the specification number, so "03.40" became both "23.040" (for 2G) and "23.140" (for 3G).
When GSM maintenance and development was transferred to 3GPP in July 2000, the 2G specification numbering was split. GSM prior to Release 4 was numbered, as always, 1 to 13. GSM Release 4 and onward was numbered 41 to 53 (add 40). UMTS Release 1999 and onward were numbered as described, from 21 to 35 (add 20).
— R.H.
