 tends to be the comparable sales approach, in which the price charged for the hypothetical transaction in question is determined by prices charged in actual market transactions involving similar goods. Two types of market transactions can serve as external benchmarks for comparable sales. The easiest case occurs when a network owner sells into an external market the same type of access mandated by the government. In that situation, market value determination is simple because comparable sales can serve as a reliable proxy for the services provided. In addition, market value may be inferred from the price charged for access to a substitute transmission technology providing similar services. Although the historical balkanization of communications has long made such determinations impossible, platform competition has made resort to this type of external bench- mark increasingly feasible. Admittedly, transactions involving substitute technolo- gies can be more difficult to apply as benchmarks than transactions using the same type of network. Differences in network configuration can complicate direct com- parisons between alternative technologies. For example, although cable television and digital broadcast satellite (DBS) systems have emerged as direct competitors, the wire-based distribution of cable operators is necessarily restricted to a limited geographic area, whereas the footprint of DBS providers is inherently national in scope (Yoo 2003b). In addition, different network technologies provide different performance and reliability levels. As a result, prices must be adjusted to reflect Networks in Telecommunications differences in the type of network before any comparisons can be drawn. However complicated such adjustments can be, they are by no means SO intractable as to ren- der transactions occurring on alternative networks useless as external benchmarks for inferring market prices. The other principal market-based valuation method is the income capitalization approach. When commercial property is involved,