By J.C. Proano, Jane Gambill, Lucent Technologies
Many MSOs (multi-system
operators) are providing telephony service and Internet access as well as entertainment video. These are usually provided in today’s market as three separate networks – a video network, based on a hybrid fiber-coax infrastructure, a data network, built on the HFC infrastructure using CableLabs’ DOCSIS specifications, and telephony network, also built on the HFC infrastructure. Some MSOs are considering combining the data and telephony networks, to reduce the cost of network implementation and maintenance. Two approaches are considered: (1) Providing an IP telephony network on top of the DOCSIS network, using the CableLabs’ PacketCable specifications, and (2) Providing IP telephony access to existing telephony equipment in the headend. The latter approach allows existing circuit switches deployed by an MSO or other service provider to provide telephony service to cable users on an IP based cable access plant. This scenario allows a migration from circuit based telephony to packet based telephony. Normalized costs are evaluated. From an end-user perspective and from an access network perspective – the two approaches are transparent. However from a service provider and network architecture perspective, the two approaches are vastly different.