CableLabs announced the results of its first testing wave for DOCSIS Set-top Gateway (DSG) testing wave yesterday. CableLabs awarded 'verified for interoperability' status to a DSG-capable set-top box from Scientific-Atlanta, and qualification status to three cable modem termination systems (CMTSs) implementing DSG functionality. The CMTSs are a DOCSIS 1.1 CMTS from BigBand Networks, and DOCSIS 2.0 CMTSs from Arris and Motorola. DSG is designed to use a DOCSIS cable modem embedded in a digital set-top to handle out-of-band (OOB) video control signaling through a CMTS, rather than using a different component in the set-top box (STB) that communicates with specialized headend gear. The use of DSG can help simplify digital STB designs, and thus, reduce their costs. For example, in set-tops that already include a DOCSIS modem, consolidating OOB functionality in the DOCSIS channel allows the number of tuners in the box to be reduced from three to two. More importantly, using DSG will allow MSOs to phase out investments in costly specialized OOB headend gear and avoid the need to allocate extra RF spectrum for OOB signaling transport, an especially precious resource in the cable return path. While the DSG approach does require a CMTS software upgrade to communicate with DOCSIS-enabled STBs, legacy STBs need not be changed, as they can continue to operate with their existing OOB system.