Перевод (часть 2)

Also, the SSG communicates with NAS over an IP-based  LAN or WAN. The NAS and SSG, then, can be installed at the same facility or distributed over multiple locations. Such flexibility gives the carrier or ISP a variety of deployment options.
By locating multiple NAS units at each CO, all controlled by a single SSG, carriers can pick up incoming calls at the originating switch and bypass not only the end office (Class 5) switch, but the rest of the circuit-switched network as well. This approach also facilitates load balancing by enabling the SSG to route calls from busy sites to alternate sites with available ports, letting the carrier provision ports based on average rather than peak loads.
Relative to traditional Internet-access approaches, this bypass technique provides significant per-port savings. In the past, carriers have had to provision one port on the RAS ($200) and one port on the end-office Class 5 switch ($1600) for each port that they offer. Bypassing now reduces the total cost per port from $1800 to just $200, gateway included. Furthermore, there’s no need for a Class 5 switch.
Another way the BypaSS7 cuts capital expenditures is by reducing the number of points of presence (POPs) the carriers must deploy to provide toll-free, local access for their customers.  A POP is a long -distance carrier’s office in a local community. In the past, this has required smaller ISPs to install POPs everywhere, because these ISPs provide their customers with fixed, local access.