The Cisco CVA122 Cable Voice Adapter functions at the most basic level as a cable modem - a modulator/demodulator that provides high-speed network access on the cable television system to residential subscribers.The Cisco CVA122 Cable Voice Adapter is based on the Data-Over-Cable Service Interface Specifications (DOCSIS), a standard developed with service providers to ensure that any DOCSIS-certified cable modem can interoperate with any bidirectional, DOCSIS-qualified CMTS.