I get by with a little help from my friends
-John Lennon, Paul McCartney, The Beatles.
Support services are necessary for the operation of any shared system or WAN, especially in a commercial offering. These services are not always visible to users of the network-in fact they probably shouldn't be-but they are essential to the operation of such a network. The need for support services is amplified in a large public mobile data network such as CDPD because the opportunities for failure, fraud and unaccounted resource usage are much greater from an operational perspective than in non-mobile networks.
Our goal in this chapter is to present both an overview of the support services necessary for any mobile WAN and a description of how these services are provided in CDPD. Security services are considered to be support services and are separately described in Chapter 6. We shall continue the discussion with network management, usage accounting, message handling, directory services and subscriber profile maintenance services. The inclusion of these support services in the basic system definition of CDPD is a distinguishing feature of this system.