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Cable Modem VoIP

Voice over Internet Protocol transmits voice signals in real-time over the Internet or IP network using your broadband Internet connection. VoIP works by sending voice information in digital form in packets. You make and receive calls as you would on a regular phone; the only difference is that calls travel over the Internet instead of over a phone line.

A number of companies offer voice over Internet protocol. Vonage is the largest in this niche industry with 260,000 phone lines running through its service. Now many cable companies are leaping into the fray by adding VoIP services to their service repertory. Cablevision Systems and Charter Communications, for example, now rely on it for all of their voice services.

In their eagerness to provide multi-tiered service, Cox and Comcast offered service over the Public Switched Telephony Network (PSTN). Although initially a network of analog telephone systems, the PSTN is now almost completely digital. Comcast currently has over one million conventional phone customers. However, both Cox and Comcast have declared their intentions to transfer phone service to VoIP, continuing to service their current customers but using VoIP to increase their telephony business. 

Switching over to VoIP services poses a number of issues. First and foremost, call quality is an ongoing concern on VoIP networks. When information travels over the Internet, it is difficult for voice services providers to ensure that information moves from the sender to the receiver in a timely manner.

The cable companies have designed their voice services so they don't travel over the public Internet, but instead run over cable vendors' private data networks, which enable them to exercise the control needed.  In order to guarantee acceptable voice quality, the cable companies’ voice services don’t use the public Internet. Instead they employ their own private networks, which are completely under their control.

PacketCable-based VoIP cable modems include ports for telephone connectivity in addition to USB and Ethernet interfaces for data connections. The modem is designed to meet Network Calling Signaling standards to ensure interoperability with all major cable broadband call systems. The modem allows high-speed broadband Internet services and tiered bandwidth options, as well as multimedia applications, such as video on demand. It allows operators to isolate services and different frequencies to guarantee the performance and guarantee the bandwidth that each of these services are allocated, which is especially important on the VoIP side if someone picks up the phone and dials - especially if it's a primary line.

Electrical outages are another problem. Conventional phones still work during power outages, but Internet-based services need electricity to keep working. To address the problem, some vendors have created back-up batteries that automatically activate when there is a loss of power.