r. The operation of a telecommunications network requires management of the interaction between operations support systems (OSS) and network elements. The production functions for telecommunications networks are summaries of complicated engineering designs. Queuing theory is a widely used planning method for network design. Queuing analysis is employed in "switched networks, local area networks, wide area data networks, multilink networks," as well as "multiprocessor multimemory computing systems" (Saadawi et al. 1994, p. 79). Queuing theory provides models of the performance of a network subject to random arrival of demands for service and capacity constraints. By specifying the capacity of nodes and links, the models yield predictions about performance. The performance of the network is the output of network services. The capac- ities of the nodes and links are the productive inputs. The structural relationship between the output of network services and the inputs of network capacity defines the network's economic production function. To illustrate these issues, without a complete tour of queuing theory, consider a simple communications network consisting of two nodes and a connecting link. The network handles demand in the form of calls, at a rate of a calls per second. The calls transmitted or handled by the network could be voice calls, data packets, messages, or other types of communications. Calls are handled in the order in which they are received. Calls have a random duration. The capacity of the network is represented by a service rate of u calls per second. The service rate takes account of the capacity of the system as well as random call duration. The load on the system is the ratio of the rate at which calls are received to the rate at which calls are served. 10 Because calls can exceed the capacity of the system, they form a queue. To prevent infinite queues, assume that the load on the system N/U is less than one. 11 The process of call arrival and servicing just 10 The load on the system is also 