過去文獻中多提出「顧客的採用決策對彼此的效用具有正向網路外部性效果」，但此假設未必與實際世界相符，反而可能會使企業對市場有過度樂觀的評估，造成企業錯誤的決策。 本文乃希望提出一個包含兩群具有不同效用函數形式的顧客的網路外部性模型，以更正確地描述真實世界中技術的採用。透過效用函數的模型比較，發現若實際世界中顧客依效用函數形式區分為兩群時，誤認顧客有相同效用函數形式的模型將會錯誤地認定目標顧客、錯誤地定價且高估收益，而差別取價的能力亦無助於收益高估量的降低。本研究也發現特殊使用者的數目對收益高估量有平方形式的影響、正常使用者的數目對收益高估量則有線性形式的影響。

Since some researchers proposed that the adoption decision of customers have mutually positive network externalities that is not always correct, this paper aims to illustrate the impact of overoptimitism on the issue of mutually positive network externalities by offering a model to include 2 groups of customers, general and special ones, fitting real situations of communication networks. Our first result shows that if the model does not consider the effect of heterogeneity of 2 groups of customers, the system owner will set a much higher price and expect to generate huge revenues. Secondly, the effect of price discriminations between 2 groups of customers doesn't play any important roles in reducing the overoptimistic expection of revenues. Finally, the overoptimistic expection of revenues is squarely influenced by the number of special customers and linearly influenced by the number of general customers.