The cable industry has expanded its competitive offerings to include business and residential telephone services delivered over its fiber optic infrastructure. A cable system can offer telephone service over the same cable line that already carries digital video, high-speed Internet and other advanced services to consumers. Cable companies are certified local exchange carriers offering competitive residential voice services across the country.
Many cable companies have launched digital phone service (often known as VoIP — Voice over Internet Protocol). Through the use of software, digital phone service provides all of the functionality of the traditional switched telephone network, while making possible new features not available through traditional circuit-switched telephony. Calls are placed over an IP-based data network and voice is transmitted with data “packets.” Facilities-based cable phone service transports these IP data packets over their private managed IP networks with end-to-end quality of service monitoring (while still interconnecting with the public telephone network as necessary).