Priority Handling of Essential User Calls in an Overloaded Distributed Switching System

Many of the newest switching systems have a distributed architecture in which the overload controls can also be distributed. Under overload, the location of the congestion might determine the type of overload control exercised. In particular, control actions may be taken even after digits have been collected. Such "post-dial" controls facilitate preferential treatment of certain calls on the basis of dialed digits. In this paper we present the results of a performance study of strategies for giving priority treatment to essential user calls at the predial and postdial stages in a distributed switching system.