PDF of this tutorial
Remember when the “busy-out” message was pretty much limited to holidays? Seasonable and predictable, that message was not so much bothersome as a simple reminder that an unusually high number of families were using the PSTN to eliminate distances at an important time. Wait a few minutes, dial again, and a connection was likely.
The success of the Internet and the World Wide Web has changed all that, producing a challenging traffic environment for the PSTN and making the busy-out message a common occurrence. Dial-up Internet calls have dramatically increased both the number of connections and average call hold times, and network load is skyrocketing. Carriers, unable to economically scale their networks to meet exploding demand, have attempted to mitigate the problem with a variety of stopgap measures. These measures, typically “trunk-side” or post-switch solutions, have met with limited success because they only move the problem upstream rather than eliminate it. Consumer demand for circuits continues to pose a significant threat to the PSTN.
As mentioned, this tutorial will explore an economical and effective solution: preswitch offload. This approach expands off-load to the line-side of overloaded switches, leverages the economies of the public data network for transport on the trunk side, and coexists with current infrastructure. Very important, implementation of this solution represents a tremendous cost savings for carriers. Equally important, preswitch offload is a strategic investment in the next-generation network, providing a scalable infrastructure solution that is an important step toward truly converged data and voice.
