Plain old telephone service will not be plain for much longer. With broadband (DSL, cable, wireless) access to the home, voice will simply be another application in everyone's home. The available features listed in the previous list are just the tip of the iceberg. This chapter discussed enhanced services, where the PSTN operators make a hefty portion of their revenue.
The PSTN offers many valuable services to subscribers and is critical to the operation of small, medium, and large businesses. These subscribers and businesses are, however, increasingly relying on the power and value of data networking and the Internet. To this end, the PSTN services discussed in this chapter as well as new voice services will, over time, be delivered over data networks and the Internet.