cdma2000 is a name identifying the third generation technology that is an evolutionary outgrowth of cdmaOne offering operators who have deployed a second generation cdmaOne system a seamless migration path that economically supports upgrade to 3G features and services within existing spectrum allocations for both cellular and PCS operators. cdma2000 supports the second generation network aspect of all existing operators regardless of technology (cdmaOne, IS-136 TDMA, or GSM). This standard is also known by its ITU name IMT-CDMA Multi-Carrier (1X/3X). It has been adopted by operators in the U.S., Japan and South Korea. Similar to, but incompatible with W-CDMA.