 Two of the most popular telecom systems were the ROLM CBX and ROLM Redwood (PBX and Key Systems Unit (KSU) models, respectively).The CBX was meant to directly compete with Northern Telecom's SL-1, AT&T Dimension telephone systems and other computerized digital-voice systems being developed at the time.By 1980, ROLM had shot past AT&T in number of systems deployed to become the #2 PBX in North America.