Complex sentence: NGMN is organized as an association of about 60 partners from the mobile telecommunications industry and research of which about 1/3rd are mobile operators, represent well over one half of the total mobile subscriber base world-wide.
Split into simpler sentences: NGMN is organized as an association of about 60 partners from the mobile telecommunications industry and research. About 1/3rd are mobile operators, representing well over one half of the total mobile subscriber base world-wide.