IMT-2000 is an acronym for "International Mobile Telecommunications-2000", aka the Third Generation Mobile Systems. This is an effort by ITU to provide "mobile telecommunications - Anywhere - Anytime". Their goal is not to single out any one technology, but rather to "think big" and make sure that different technologys can co-exist, eg. phones using both indoors and outdoors networks.
http://www.itu.int/imt/