A 3G technology that is an evolutionary outgrowth of cdmaOne. It offers operators who have deployed a 2G cdmaOne system a seamless migration path to 3G. cdma2000 supports the 2G 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). cdma2000 has been divided into 2 phases. The first phase capabilities are defined in a standard known as 1X, which introduces 144 kbps packet data in a mobile environment and speeds beyond this in a fixed environment. cdma2000 phase two, known as 3X, incorporates the capabilities of 1X. It also supports all channel sizes (5 MHz, 10 MHz, etc.), provides circuit and packet data rates up to 2 Mbps, incorporates advance multimedia capabilities, and includes a framework for advanced 3G voice services and vocoders, including voice over packet and circuit data.