本文討論兼營業務管級解除之後，獨占經營市內電話之電信業者，在受到報酬率管制的情況下，利用跟營業為手段，追求最大利潤的行為及所形成的費率結構。本文建立新模式，將文?中認為會促史獨占者調整跟營業產量的兩項誘因，一齊加入模式之中。此兩項誘因（共同成本分比例及費率基礎的調整）的存在，使得兼營業務的資金不論納不納入合理報酬率管級之中，都會使費率結構有不具效率性的情形發生。文中周時對於，應和何將兼營業務與獨占業務之產量組合進行調整，以獲得效率的改顧，進行初步的分析。

　　　　　Removing bundling (or tying) regulation allows a regulated monopoly to diversify into unregulated markets. In such a partially deregulated circumstance, telephone companies are permitted to participate in both regulated and unregulated markets. In this paper, we wish to understand the effects of using the combined capital if both market activities (regulated and unregulated business) were used to define the rate base of rate-of-return regulated company. Two kinds of incentive for a regulated company to choose outputs levels are discussed. We find that combining regulated and unregulated business activities under the regulatory umbrella may have deleterious effects on allocative efficiency in unregulated markets.