Summarized from Telcordia's (the new name for Bellcore) home page:
Originally was the Central Services Organization of AT&T, renamed as Bell Communications Research (Bellcore) when AT&T divested the Regional Bell Operating Companies (RBOCS). Bellcore was jointly owned by the RBOCs until it was acquired by Science Applications International Corporation (SAIC).
Bellcore has been responsible for many technology innovations, primarily in communications. Additionally, Bellcore was also responsible for administrating the North American Numbering Plan (NANP).
In 1999, Bellcore was renamed Telcordia.