PART I Operating Costs and Expenses by Business Segment  Domestic fixed communications  Mobile communications  Internet  International fixed communications  Others  Income from operations and Operating Margin  81 As a result of the foregoing, our income from operations decreased by 3.7% from NT$58.6 billion in 2008  to NT$56.4 billion in 2009. Our operating margin decreased from 29.0% in 2008 to 28.5% in 2009.  Our costs and expenses from our other business increased by 21.1% from NT$3.8 billion in 2008 to  NT$4.6 billion in 2009. The increase was primarily due to the consolidation of our subsidiaries.  Our international fixed communications costs and expenses decreased by 2.6% from NT$14.6 billion  in 2008 to NT$14.2 billion in 2009. The decrease was primarily due to a decrease of NT$0.6 billion in  interconnection fees and a NT$0.3 billion decrease in connection fees. Our depreciation and amortization  expenses relating to international fixed communications business increased by 5.9% from NT$1.3 billion in 2008  to NT$1.4 billion in 2009. The slight increase is mainly due to an increase in capital expenditures.  Our internet operating costs and expenses increased by 11.5% from NT$13.5 billion in 2008 to NT$15.1  billion in 2009. This increase was primarily due to a NT$0.6 billion increase in leased line expenses and a  NT$0.5 billion increase in expenses related to our corporate solution services and ICT. Our depreciation and  amortization expenses relating to our internet business decreased by 1.1% from NT$2.4 billion in 2008 to  NT$2.3 billion in 2009. The decrease is mainly due to a slowdown in capital expenditures.  Our mobile communications operating costs and expenses increased by 1.0% from NT$57.7 billion in  2008 to NT$58.3 billion in 2009. This increase was primarily due to an increase of NT$1.1 billion in leased  line expenses and an NT$0.3 billion increase in connection fees. Our depreciation and amortization expenses  relating to mobile communications business decreased by 5.5% from NT$8.9 billion in 2008 to NT$8.4 billion  in 2009. This decrease was mainly due to a decrease in depreciation expenses reflecting a slowdown in capital  expenditures.  Our domestic fixed communications costs and expenses decreased by 2.6% from NT$69.5 billion in 2008  to NT$67.6 billion in 2009, primarily due to a NT$0.6 billion decrease in material costs and expenses. Our  depreciation and amortization expenses relating to our domestic fixed communications business decreased by  5.9% from NT$25.5 billion in 2008 to NT$24.0 billion in 2009. The decrease was primarily due to a decrease in  depreciation expenses reflecting a slowdown in capital expenditures.  Domestic Fixed  Communications Mobile  Communications Internet International  Fixed  Communications Others Adjustment Total For the year ended  December 31, 2009 Operating costs and expenses 67.6  58.3  15.1  14.2  4.6  (17.8)  142.0  Depreciation and amortization 24.0  8.4  2.3  1.4  0.2  — 36.3  For the year ended  December 31, 2008 Operating costs and expenses 69.5  57.7  13.5  14.6  3.8  (16.0)  143.1  Depreciation and amortization 25.5  8.9  2.4  1.3  0.1  — 38.2 