2005年10月,台灣電信市場開始實施行動電話號碼可攜式服務,此後消費者於繳交移轉手續費後,在轉換行動電話服務公司時將可不須更改原有門號,這項制度降低消費者在轉換行動電話服務公司時的成本,並使市場競爭程度更加的強烈。本研究採用Train (2003)所提出的羅吉特模式,估算台灣行動電話市場在號碼可攜式服務下的轉換成本。實證結果顯示,消費者繳交的移轉手續費僅占所有轉換成本的小部分,因此推論號碼可攜式服務將會降低轉換成本並提升台灣行動電話市場的競爭程度。 Mobile number portability (MNP) was implemented in Taiwan as of October 2005. Under number portability, the consumers can switch mobile communications providers without changing their phone number after paid the switching fees. MNP in the mobile communications market is believed to play an important role in lowering switching costs which can increase the level competition among providers. The aim of this study is to estimate the switching costs under MNP in the Taiwan mobile communications market using the logit model of Train (2003). The analysis shows that the switching fees have made up only a small fraction of the total switching costs that consumers have faced. In other words, number portability is meaningful in the sense that it helps promote competition in the Taiwan mobile communications market by reducing the cost of switching.