de better benchmarks for UNE services. Networks are greater than the sums of their parts. Far from being collections of elements snapped together like tinkertoys, networks are interconnected in irre- ducible ways. Beginning with engineering specifications and technology, networks are designed to make the best use of inputs to achieve performance standards. This process generates an economic production function that reflects all of the techni- cally efficient combinations of inputs needed to produce network services. Then Networks in Telecommunications the network operator chooses the least-cost mix of inputs to produce a particu- lar set of network services. The economic cost function is the schedule of costs associated with network outputs. As we will see, the profit-maximizing mix of net- work outputs is chosen based on relative costs to the network operator and relative benefits to consumers of network outputs. Thus, the decision processes associated with engineering design, production functions, cost functions, and profit functions determine network architecture and the configurations of network elements. The set of connections between network elements is reflected, for example, in the cost of UNE services. It is not possible to evaluate the separate cost of UNEs after the fundamental change takes place when these elements are incorporated in the network. Instead, the network operator must evaluate the cost of providing the services of UNEs within the three-step process of engineering design, production function specification, and cost minimization. The science of networks principally shows that networks function as inte- grated systems, SO that understanding individual components cannot provide a full appreciation of the properties of the network. Regulation that is based on access to individual network elements or on the costs of those elements may not reflect an understanding of the effects of regulations on the network as a whole. Com- munications networks function as unified systems in many ways. The net