RBOC

RBOC stands for regional Bell Operating Companies.  In 1983, the very large US Bell Telephone company (ATT) was considered too large and it was broken up into 7 smaller operating companies plus ATT as an eight entity.  ATT was to be an equipment corporation and long distance service.  The 7 RBOCs were:  Pacific Telesis, Bell South, Southwest Bell, Nynex (New York), Ameritech, US West, and Bell Atlantic.  These RBOCs over time also spun off wireless branches, such as Pac Tel, BAMs (Bell Atlantic Mobile)  and others.  Several of these wireless branches evolved into some of the wireless operators in the US today.