各國自 1980 年代開始自由化電信市場時，紛紛改採用較具有效率誘因的價格調整上限法管制零售價格，以電信業者技術或服務創新所帶來的效率增加⎯⎯所謂的效率因子或調整係數 X 值⎯⎯扣除通貨膨脹或其他總體經濟變數變動後之數值，作為其調整價格之上限。國家通訊傳播委員會（ NCC）審酌電信事業生產經營效率、各國費率水平及平均降幅、各國監理機關所訂X 值範圍及保障消費者權益等五個因素，於 2006 年底公告新的 X 值： ADSL電路出租為△CPI + 5.35%， 900 兆赫及 1800 兆赫行動電話業務中市話撥打行動電話的服務、預付資費方式的服務及月租型服務之不同費率選單中通信費單價最高者，均為△CPI + 4.88%。本文回顧實施零售價格調整上限制最有經驗的英國與美國聯邦（而不包括各州的零售價格管制），發現該制均盛極而衰，走向結束。本文檢討 NCC 調整 X 值之作法中三點可檢討之處： 1.未要求中華電信舉證其 ADSL 之成本與利潤，錯失進一步合理降低 ADSL 價格的機會； 2.要求連續三年調降月租型行動電話服務不同費率選單中通信費單價最高通信費 4.88%，並非針對競爭不足的特定業務； 3.未充分說明調整係數X 之組成元素。本文最後點出事前管制零售價格的必要性會日益降低，故應該加強電信業者間資費管制的研究與規範。

When liberalizing telecom markets in the 1980s, countries world over adopted the price cap regime to regulate retail prices that telecom companies may charge their customers. Under price cap telecom companies may not raise the retail prices above the level where efficiency gains—commonly known as the efficiency factor or X factor－ minus inflation rate. The National Communications Commission (NCC) promulgated new X factors for various telecom services at the end of 2006: X for ADSL is △CPI + 5.35%, X for the following three mobile services that utilize 900MHz and 1800MHz spectrums is △CPI+4.88%: local phones calling mobile phones, prepaid services and services that charge the highest unit rates. This paper examines price cap practices in the UK and USA and determines that its importance is declining. This paper then critically reviews the adjustment of X factors made by the NCC and finds three flaws: 1. The NCC failed to further reasonably reduce ADSL prices. 2. Services that charge the highest unit price do not necessarily suffer from insufficient competition. 3. There lacks a clear explanation about the composition elements of the X factor. In conclusion it points to the fact that retail price regulation is not to be maintained in the long run and more attention shall be shifted to the study and regulation of prices among telecom service providers.

價格調整上限制;報酬率管制法;調整係數 X 值;電信法;國家通訊傳播委員會; NCC;通傳會

price cap; rate of return; X factor; telecom law; NCC; National Communications Commission