26 P AR T I The following table sets forth information with respect to our local telephone customers and penetration rates as of the dates  indicated.  We provide local telephone services to approximately 12.08 million customers in Taiwan. Our fixed line network reaches  virtually all homes and businesses in Taiwan. Revenues from local telephone services comprised 16.7%, 15.9% and 19.2% of our  total revenues in 2009, 2010 and 2011, respectively. Approximately 74.1 % of our local telephone customers as of December 31,  2011 were residential customers. We are currently the leader of the local telephone service market, with an average market share of  approximately 97.1%, 96.9% and 95.3% in 2009, 2010 and 2011, respectively.  Year ended December 31, 2009 2010 2011 NT$ NT$ NT$ US$ (in billions) (in millions) Local telephone revenues: Usage 10.6 10.0 21.0  693.0 Subscription 17.2 17.0 16.7  552.2  Interconnection 2.5 2.4 1.4  43.8  Pay telephone 0.6 0.5 0.4 14.6  Other 2.3 2.9 2.2  88.5  Total 33.2 32.3 41.7 1,392.1 The following table sets forth our revenues from local telephone services for the periods indicated.  Local Telephone  The provision of domestic fixed communications services is one of our principal business activities. Our domestic fixed  communications business includes local and domestic long distance telephone services, broadband access services, local and  domestic long distance leased line services, multimedia on demand services, and domestic other services. We are the largest provider  of local and domestic long distance telephone services in Taiwan. We also provide interconnection with our fixed line network to  other mobile and fixed line operators. Since June 2001, three new operators have begun offering fixed line services. Our revenues  from domestic fixed communications services were NT$71.5 billion or 36.0% of our revenues in 2009, NT$70.7 billion, or 34.9% of  our revenues in 2010 and NT$79.4 billion, or 36.5% of our revenues, in 2011. In general, we expect that revenues from our domestic  fixed communications business as a percentage of our total revenues will continue to decline primarily due to the expansion of  our mobile communications services and the general trend of a continued decline in fixed line voice traffic. In 2011, however, our  domestic fixed communications business increased as a percentage of our total revenues due to the change in pricing and collections  policies for fixed line-to-mobile phone calls. Since January 1, 2011, the fixed line operator now sets and collects the tariffs for fixed  line-to-mobile phone calls, whereas prior to January 1, 2011, these functions were performed by the mobile operator. Please see “Item  4. Information on the Company—B. Business Overview—Regulation—Interconnection Arrangements”. Our core business segments are our domestic fixed communications business, mobile communications business, internet  business and international fixed communications business.  Domestic Fixed Communications Business  Our Principal Lines of Business  B. Business Overview 