hnicalPDF.com Improved compression and other techniques such as rate shaping provide the capability to carry additional video and broadband traffic. Rate shaping adds capacity by using a form of over-subscription. It's analogous to pouring one-and-a-quarter quarts of water into a pail that holds only a single quart. Rate shaping equipment discards bits in real time SO that adding 8 megabits of traffic to a 6-megabit channel does not impact quality. This assumes that not everyone will be watching TV at the same time. Legacy Circuit-Switching Service Switched services operate on landline and cellular networks that use older mobile protocols. When a person makes a call, the network sets up a path between the caller and the dialed party. Importantly, the path is available exclusively for the duration of the call. The path is not shared. Natural pauses in conversation and data transmission are not used for other voice or data calls. Capacity is reserved in the network for the entire duration of the transmission. This exclusivity causes wasteful utilization of network capacity. Circuit switching is being gradually phased out in public networks. Carriers increasingly add IP equipment when replacing fully depreciated, older voice switches or when building new infrastructure. Last-mile access networks use a mix of primarily IP and some circuit switching to carry voice. Traditional telephone companies and cable TV providers are in the process of transitioning to IP in their last-mile networks. When customers select their telephone provider for Internet access and TV services, the provider offers to move the subscriber's voice service to the same broadband infrastructure as that used for data and TV. Most of them provide VoIP over the broadband. Transitioning Customers to Voice over Internet Protocol and Fiber www.TechnicalPDF.com Data and video are the largest source of traffic on landline networks, far exceeding the shrinking amounts of voice. Many providers now transmit voice in packets, the same format as data, as a way