The operating segments are managed separately because each operating segment represents a strategic  business unit that serves different markets. The Company’s measure of segment performance is mainly based  on revenues and income before tax.  a.  Segment information  Domestic Fixed  Communications  Business  Mobile  Communications  Business  Internet  Business  International  Fixed  Communications  Business  Others  Adjustment  Total  NT$ NT$ NT$ NT$ NT$ NT$ NT$ Year ended December 31, 2008 Revenues from external customers $  73,058 $  88,808 $  23,022 $  15,936 $  846 $  — $  201,670  Intersegment service revenues 11,929 1,933 563 1,527 2 (15,954) — Interest income  3 14 4 35 1,860 — 1,916  Other income  209 175 22 34 1,020 — 1,460  $  85,199 $  90,930 $  23,611 $  17,532 $  3,728  $  (15,954) $  205,046  Interest expense  $  — $  1 $  2 $  — $  1 $  — $  4  Depreciation and amortization $  25,501 $  8,859 $  2,354 $  1,326 $  176 $  — $  38,216  Other expense  $  324 $  37 $  9 $  2 $  1,843 $  — $  2,215  Segment income before tax  $  15,473 $  33,175 $  10,086 $  2,911 $  (1,961) $  — $  59,684  Total assets  $  243,102 $  66,971 $  17,004 $  18,244 $ 118,269 $  — $  463,590  Capital expenditures for segment assets $  20,710 $  5,207 $  2,186 $  1,200 $  816 $  — $  30,119  Year ended December 31, 2009 Revenues from external customers  $  71,467 $  86,524 $  23,653 $  15,244 $  1,473 $  — $  198,361  Intersegment service  revenues  13,650 1,915 717 1,523 3 (17,808) — Interest income  3 8 4 11 453 — 479  Other income  77 104 74 10 678 — 943  $  85,197 $  88,551 $  24,448 $  16,788 $  2,607 $  (17,808) $  199,783  Interest expense  $  3 $  1 $  10 $  —  $  1 $  — $  15 Depreciation and  amortization  $  23,984 $  8,373 $  2,327 $  1,404 $  232  $  — $  36,320 Other expense  $  156 $  98 $  11 $  2 $  279 $  — $  546 Segment income before tax  $  17,452 $  30,184 $  9,356 $  2,550 $  (2,304) $  — $  57,238 Total assets  $  231,177 $  63,537 $  17,154 $  18,700 $  118,429 $  — $  448,997 Capital expenditures for segment  assets  $  15,877 $  5,028 $  2,097 $  1,299 $  1,177 $  — $  25,478 Year ended December 31, 2010 Revenues from external customers $  70,688  $  89,044  $  24,483 $  15,534  $  2,681 $  — $  202,430 Intersegment service revenues ...... 14,662  2,117  1,104 1,720  750 (20,353) — Interest income 1  9  2 9  454 — 475 Other income 31  263  24 96  313 (170) 557 $  85,382  $  91,433  $  25,613 $  17,359  $  4,198 $  (20,523) $  203,462 Interest expense $  75  $  1  $  7 $  — $  24 $  — $  107 Depreciation and amortization $  21,948  $  8,205  $  2,206 $  1,383  $  322 $  — $  34,064 Other expense $  283  $  7  $  14 $  198  $  255 $  (170) $  587 Segment income before tax $  18,048  $  29,328  $  9,835 $  2,652  $  (2,176) $  — $  57,687 Total assets $  227,376  $  63,330  $  17,663 $  23,535  $  122,407 $  — $  454,311 Capital expenditures for segment  assets $  14,260  $  5,261  $  1,889 $  1,787  $  1,420 $  — $  24,617 F-58