• IMT-2000 is a family of technologies for 3rd Generation mobile communications, and has been defined by the International Telecommunication Union (ITU)
• It is in the mid-1980s that the concept for IMT-2000, "International Mobile Telecommunications", was born at the ITU. After over ten years of hard work under the leadership of the ITU, a historic decision was taken in the year 2000: unanimous approval of the technical specifications for third generation systems under the brand IMT-2000.
• The entire telecommunication industry, including both industry and national and regional standards-setting bodies gave a concerted effort 1to avoiding the fragmentation that had thus far characterized the mobile market. This approval meant that for the first time, full interoperability and interworking of mobile systems could be achieved. IMT-2000 is the result of collaboration of many entities, inside the ITU (ITU-Rand ITU-D, and outside the ITU (3GPP, 3GPP2, UWCC and so on)
• The spectrum between 400 MHz and 3 GHz is technically suitable for the third generation. The number 2000 in IMT-2000 should indicate the start of the system (year 2000+x) and the spectrum used (around 2000 MHz).
• IMT-2000 offers the capability of providing value-added services and applications on the basis of a single standard.
• The system envisages a platform for distributing converged fixed, mobile, voice, data, Internet and multimedia services.
• One of its key visions is to provide seamless global roaming, enabling users to move across borders while using the same number and handset.
• IMT-2000 also aims to provide seamless delivery of services, over a number of media (satellite, fixed, etc. .. ).
• IMT-2000 provides higher transmission rates: a minimum speed of 2Mbit/s for stationary or walking users, and 348 kbit/s in a moving vehicle. Second-generation systems only provide speeds ranging from 9.6 kbit/s to 28.8 kbit/s. 
• In addition, IMT-2000 has the following key characteristics:

1.    Flexibility

With the large number of mergers and consolidations occurring in the mobile industry, and the move into foreign markets, operators wanted to avoid having to support a wide range of different interfaces and technologies. This would surely have hindered the growth of 3G worldwide. The IMT-2000 standard addresses this problem, by providing a highly flexible system, capable of supporting a wide range of services and applications. The IMT-2000 standard accommodates five possible radio interfaces based on three different access technologies (FDMA, TDMA and CDMA)

2.    Affordability

There was agreement among industry that 3G systems had to be affordable, in order to encourage their adoption by consumers and operators.

3.    Compatibility with existing systems

IMT-2000 services have to be compatible with existing systems. 2G systems, such as the GSM standard (prevalent in Europe and parts of Asia and Africa) will continue to exist for some time and compatibility with these systems must be assured through effective and seamless migration paths.

4.  Modular Design

The vision for IMT-2000 systems is that they must be easily expandable in order to allow for growth in users, coverage areas, and new services, with minimum initial investment.

As a single standard couldn't be found, ITU standardises 5 groups of radio access technologies under I MT 2000 family, as follows:

1.    IMT-DS:

The direct spread technology comprises wideband CDMA (WCDMA) systems. This is the technology specified for UTRA-FDD and used by all European providers and the Japanese NIT DoCoMo for 3G wide area services. To avoid complete confusion ITU's name for the technology is IMT-DS, ETSI called it UTRA-FDD in the UMTS context, and technology used is called W-CDMA. Today, standardization of this technology takes place in 3GPP.

2.    IMT-TC:

Initially, this family member, called time code, contained only the UTRA-TDD system which uses time-division CDMA (TD-CDMA). Later on, the Chinese proposal, TD-synchronous CDMA (TD-SCDMA) was added. Both standards have been combined and 3GPP fosters the development of this technology. It is unclear when and to what extent this technology will be introduced. The initial UMTS installations are based on W-CDMA.

3.    IMT-MC:

CDMA2000 is a multi-carrier technology standardized by 3GPP2 (Third generation partnership project 2, 3GPP2, 2002), which was formed shortly after 3GPP to represent the second main stream in 3G technology. Version cdma2000 EV-DO has been accepted as the 3G standard.

4.    IMT-SC:

The enhancement of the US TDMA systems, UWC-136, is a single carrier technology originally promoted by the Universal Wireless Communications Consortium (UWCC). It is now integrated into the 3GPP efforts. This technology applies EDGE, among others, to enhance the 2G IS-136 standard.

5.    IMT-FT:

As frequency time technology, an enhanced version of the cordless telephone standard DECT has also been selected for applications that do not require high mobility. ETSI is responsible for the standardization of DECT.