The call management server provides the intelligence to route calls and support residential telephony features such as call waiting, three-way calling, and calling name and number delivery. The challenge for those writing PacketCable specs is to define all these interfaces. In turn, the vendor community must develop a new set of network elements for the distributed network and perform interoperability testing. The attributes of existing circuit-switched cable telephony service provide a benchmark for IP telephony over cable. New VoIP services must have similar attributes and meet primary consumer requirements.
Consumers care less about the underlying technology than the service itself.
Therefore, it's illustrative to review consumer requirements and compare how both VoIP and circuit-switched cable telephony stack up against those requirements. Lifeline service Consumers rely on their telephones for emergency service. Therefore, service must be available during a commercial power outage. Cable telephony products provided by several vendors are much lower than 3 watts for two-line NIUs and support network power and local power with battery backup options. Premium voice quality IP telephony over cable must provide high-quality codecs, low delay and low packet loss.