First, Alphabet Soup -- SDOs

SDO == Standards Developing Organizations

ITU  -- International Telecommunication Union

3GPP -- 3rd Generation Partnership Project
Defines 3G specifications for GSM networks
Part of the ITU
3GPP2 -- 3rd Generation Partnership Project "2"
Defines 3G specifications systems based on ANSI/TIA/EIA-41 networks
Part of the ITU

ETSI -- European Telecommunications Standard Institute
Part of TISPAN (I.T. and Information Management)

ATIS -- Alliance for Telecommunications Industry Solutions

Oh yeah, and...the IETF