1 Study Coverage 1.1 Mobile Network Operator Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Introduction 1.2 Global Mobile Network Operator Outlook 2017 VS 2022 VS 2028 1.2.1 Global Mobile Network Operator Market Size for the Year 2017-2028 1.2.2 Global Mobile Network Operator Market Size for the Year 2017-2028 1.3 Mobile Network Operator Market Size, United States VS Global, 2017 VS 2022 VS 2028 1.3.1 The Market Share of United States Mobile Network Operator in Global, 2017 VS 2022 VS 2028 1.3.2 The Growth Rate of Mobile Network Operator Market Size, United States VS Global, 2017 VS 2022 VS 2028 1.4 Mobile Network Operator Market Dynamics 1.4.1 Mobile Network Operator Industry Trends 1.4.2 Mobile Network Operator Market Drivers 1.4.3 Mobile Network Operator Market Challenges 1.4.4 Mobile Network Operator Market Restraints 1.5 Study Objectives 1.6 Years Considered 2 Mobile Network Operator by Type 2.1 Mobile Network Operator Market Segment by Type 2.1.1 GPRS 2.1.2 3G 2.1.3 4G/LTE 2.1.4 5G 2.2 Global Mobile Network Operator Market Size by Type (2017, 2022 & 2028) 2.3 Global Mobile Network Operator Market Size by Type (2017-2028) 2.4 United States Mobile Network Operator Market Size by Type (2017, 2022 & 2028) 2.5 United States Mobile Network Operator Market Size by Type (2017-2028) 3 Mobile Network Operator by Application 3.1 Mobile Network Operator Market Segment by Application 3.1.1 Mobile Phones 3.1.2 Household Computers 3.1.3 Smart Homes / IoT Device 3.1.4 Enterprise Server 3.1.5 Others 3.2 Global Mobile Network Operator Market Size by Application (2017, 2022 & 2028) 3.3 Global Mobile Network Operator Market Size by Application (2017-2028) 3.4 United States Mobile Network Operator Market Size by Application (2017, 2022 & 2028) 3.5 United States Mobile Network Operator Market Size by Application (2017-2028) 4 Global Mobile Network Operator Competitor Landscape by Company 4.1 Global Mobile Network Operator Market Size by Company 4.1.1 Top Global Mobile Network Operator Companies Ranked by Revenue (2021) 4.1.2 Global Mobile Network Operator Revenue by Player (2017-2022) 4.2 Global Mobile Network Operator Concentration Ratio (CR) 4.2.1 Mobile Network Operator Market Concentration Ratio (CR) (2017-2022) 4.2.2 Global Top 5 and Top 10 Largest Companies of Mobile Network Operator in 2021 4.2.3 Global Mobile Network Operator Market Share by Company Type (Tier 1, Tier 2, and Tier 3) 4.3 Global Mobile Network Operator Headquarters, Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Type 4.3.1 Global Mobile Network Operator Headquarters and Area Served 4.3.2 Global Mobile Network Operator Companies Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Type 4.3.3 Date of International Companies Enter into Mobile Network Operator Market 4.4 Companies Mergers & Acquisitions, Expansion Plans 4.5 United States Mobile Network Operator Market Size by Company 4.5.1 Top Mobile Network Operator Players in United States, Ranked by Revenue (2021) 4.5.2 United States Mobile Network Operator Revenue by Players (2020, 2021 & 2022) 5 Global Mobile Network Operator Market Size by Region 5.1 Global Mobile Network Operator Market Size by Region: 2017 VS 2022 VS 2028 5.2 Global Mobile Network Operator Market Size by Region (2017-2028) 5.2.1 Global Mobile Network Operator Market Size by Region: 2017-2022 5.2.2 Global Mobile Network Operator Market Size by Region (2023-2028) 6 Segment in Region Level & Country Level 6.1 North America 6.1.1 North America Mobile Network Operator Market Size YoY Growth 2017-2028 6.1.2 North America Mobile Network Operator Market Facts & Figures by Country (2017, 2022 & 2028) 6.1.3 United States 6.1.4 Canada 6.2 Asia-Pacific 6.2.1 Asia-Pacific Mobile Network Operator Market Size YoY Growth 2017-2028 6.2.2 Asia-Pacific Mobile Network Operator Market Facts & Figures by Region (2017, 2022 & 2028) 6.2.3 China 6.2.4 Japan 6.2.5 South Korea 6.2.6 India 6.2.7 Australia 6.2.8 China Taiwan 6.2.9 Indonesia 6.2.10 Thailand 6.2.11 Malaysia 6.3 Europe 6.3.1 Europe Mobile Network Operator Market Size YoY Growth 2017-2028 6.3.2 Europe Mobile Network Operator Market Facts & Figures by Country (2017, 2022 & 2028) 6.3.3 Germany 6.3.4 France 6.3.5 U.K. 6.3.6 Italy 6.3.7 Russia 6.4 Latin America 6.4.1 Latin America Mobile Network Operator Market Size YoY Growth 2017-2028 6.4.2 Latin America Mobile Network Operator Market Facts & Figures by Country (2017, 2022 & 2028) 6.4.3 Mexico 6.4.4 Brazil 6.4.5 Argentina 6.5 Middle East and Africa 6.5.1 Middle East and Africa Mobile Network Operator Market Size YoY Growth 2017-2028 6.5.2 Middle East and Africa Mobile Network Operator Market Facts & Figures by Country (2017, 2022 & 2028) 6.5.3 Turkey 6.5.4 Saudi Arabia 6.5.5 UAE 7 Company Profiles 7.1 AT&T 7.1.1 AT&T Company Details 7.1.2 AT&T Business Overview 7.1.3 AT&T Mobile Network Operator Introduction 7.1.4 AT&T Revenue in Mobile Network Operator Business (2017-2022) 7.1.5 AT&T Recent Development 7.2 Verizon 7.2.1 Verizon Company Details 7.2.2 Verizon Business Overview 7.2.3 Verizon Mobile Network Operator Introduction 7.2.4 Verizon Revenue in Mobile Network Operator Business (2017-2022) 7.2.5 Verizon Recent Development 7.3 T-mobile 7.3.1 T-mobile Company Details 7.3.2 T-mobile Business Overview 7.3.3 T-mobile Mobile Network Operator Introduction 7.3.4 T-mobile Revenue in Mobile Network Operator Business (2017-2022) 7.3.5 T-mobile Recent Development 7.4 Sprint 7.4.1 Sprint Company Details 7.4.2 Sprint Business Overview 7.4.3 Sprint Mobile Network Operator Introduction 7.4.4 Sprint Revenue in Mobile Network Operator Business (2017-2022) 7.4.5 Sprint Recent Development 7.5 China Telecom 7.5.1 China Telecom Company Details 7.5.2 China Telecom Business Overview 7.5.3 China Telecom Mobile Network Operator Introduction 7.5.4 China Telecom Revenue in Mobile Network Operator Business (2017-2022) 7.5.5 China Telecom Recent Development 7.6 China Unicom 7.6.1 China Unicom Company Details 7.6.2 China Unicom Business Overview 7.6.3 China Unicom Mobile Network Operator Introduction 7.6.4 China Unicom Revenue in Mobile Network Operator Business (2017-2022) 7.6.5 China Unicom Recent Development 7.7 China Mobile 7.7.1 China Mobile Company Details 7.7.2 China Mobile Business Overview 7.7.3 China Mobile Mobile Network Operator Introduction 7.7.4 China Mobile Revenue in Mobile Network Operator Business (2017-2022) 7.7.5 China Mobile Recent Development 7.8 Telefónica 7.8.1 Telefónica Company Details 7.8.2 Telefónica Business Overview 7.8.3 Telefónica Mobile Network Operator Introduction 7.8.4 Telefónica Revenue in Mobile Network Operator Business (2017-2022) 7.8.5 Telefónica Recent Development 7.9 Vodafone 7.9.1 Vodafone Company Details 7.9.2 Vodafone Business Overview 7.9.3 Vodafone Mobile Network Operator Introduction 7.9.4 Vodafone Revenue in Mobile Network Operator Business (2017-2022) 7.9.5 Vodafone Recent Development 7.10 British Telecom 7.10.1 British Telecom Company Details 7.10.2 British Telecom Business Overview 7.10.3 British Telecom Mobile Network Operator Introduction 7.10.4 British Telecom Revenue in Mobile Network Operator Business (2017-2022) 7.10.5 British Telecom Recent Development 7.11 Deutsche Telekom AG 7.11.1 Deutsche Telekom AG Company Details 7.11.2 Deutsche Telekom AG Business Overview 7.11.3 Deutsche Telekom AG Mobile Network Operator Introduction 7.11.4 Deutsche Telekom AG Revenue in Mobile Network Operator Business (2017-2022) 7.11.5 Deutsche Telekom AG Recent Development 7.12 SK Telecom 7.12.1 SK Telecom Company Details 7.12.2 SK Telecom Business Overview 7.12.3 SK Telecom Mobile Network Operator Introduction 7.12.4 SK Telecom Revenue in Mobile Network Operator Business (2017-2022) 7.12.5 SK Telecom Recent Development 7.13 KT Corporation 7.13.1 KT Corporation Company Details 7.13.2 KT Corporation Business Overview 7.13.3 KT Corporation Mobile Network Operator Introduction 7.13.4 KT Corporation Revenue in Mobile Network Operator Business (2017-2022) 7.13.5 KT Corporation Recent Development 7.14 Orange 7.14.1 Orange Company Details 7.14.2 Orange Business Overview 7.14.3 Orange Mobile Network Operator Introduction 7.14.4 Orange Revenue in Mobile Network Operator Business (2017-2022) 7.14.5 Orange Recent Development 7.15 NTT Docomo 7.15.1 NTT Docomo Company Details 7.15.2 NTT Docomo Business Overview 7.15.3 NTT Docomo Mobile Network Operator Introduction 7.15.4 NTT Docomo Revenue in Mobile Network Operator Business (2017-2022) 7.15.5 NTT Docomo Recent Development 7.16 Softbank 7.16.1 Softbank Company Details 7.16.2 Softbank Business Overview 7.16.3 Softbank Mobile Network Operator Introduction 7.16.4 Softbank Revenue in Mobile Network Operator Business (2017-2022) 7.16.5 Softbank Recent Development 7.17 Jio 7.17.1 Jio Company Details 7.17.2 Jio Business Overview 7.17.3 Jio Mobile Network Operator Introduction 7.17.4 Jio Revenue in Mobile Network Operator Business (2017-2022) 7.17.5 Jio Recent Development 8 Research Findings and Conclusion 9 Appendix 9.1 Research Methodology 9.1.1 Methodology/Research Approach 9.1.2 Data Source 9.2 Author Details 9.3 Disclaimer

List of Tables Table 1. Mobile Network Operator Market Size United States VS Global, CAGR (2017 VS 2022 VS 2028) Table 2. Mobile Network Operator Market Trends Table 3. Mobile Network Operator Market Drivers Table 4. Mobile Network Operator Market Challenges Table 5. Mobile Network Operator Market Restraints Table 6. Global Mobile Network Operator Market Size by Type: 2017 VS 2022 VS 2028 (US$ Million) Table 7. United States Mobile Network Operator Market Size by Type: 2017 VS 2022 VS 2028 (US$ Million) Table 8. Global Mobile Network Operator Market Size by Application: 2017 VS 2022 VS 2028 (US$ Million) Table 9. United States Mobile Network Operator Market Size by Application: 2017 VS 2022 VS 2028 (US$ Million) Table 10. Top Mobile Network Operator Companies in Global Market, Ranking by Revenue (2021) Table 11. Global Mobile Network Operator Revenue by Player, (US$ Million), 2017-2022 Table 12. Global Mobile Network Operator Revenue Share by Player, 2017-2022 Table 13. Global Mobile Network Operator Companies Market Concentration Ratio (CR5 and HHI) Table 14. Global Mobile Network Operator by Company Type (Tier 1, Tier 2, and Tier 3) & (based on the Revenue in Mobile Network Operator as of 2021) Table 15. Top Players of Mobile Network Operator in Global Market, Headquarters and Area Served Table 16. Companies Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Type Table 17. Date of International Companies Enter into Mobile Network Operator Market Table 18. Companies Mergers & Acquisitions, Expansion Plans Table 19. Top Mobile Network Operator Players in United States Market, Ranking by Revenue (2021) Table 20. United States Mobile Network Operator Revenue by Players, (US$ Million), 2020, 2021 & 2022 Table 21. United States Mobile Network Operator Revenue Share by Players, 2020, 2021 & 2022 Table 22. Global Mobile Network Operator Market Size by Region (US$ Million): 2017 VS 2022 VS 2028 Table 23. Global Mobile Network Operator Market Size by Region (2017-2022) & (US$ Million) Table 24. Global Mobile Network Operator Market Size Forecast by Region (2023-2028) & (US$ Million) Table 25. North America Mobile Network Operator Sales in Value by Country (2017-2028) & (US$ Million) Table 26. Asia Pacific Mobile Network Operator Sales in Value by Region (2017-2028) & (US$ Million) Table 27. Europe Mobile Network Operator Sales in Value by Country (2017-2028) & (US$ Million) Table 28. Latin Americaa Mobile Network Operator Sales in Value by Country (2017-2028) & (US$ Million) Table 29. Middle East and Africa Mobile Network Operator Sales in Value by Country (2017-2028) & (US$ Million) Table 30. AT&T Company Details Table 31. AT&T Business Overview Table 32. AT&T Mobile Network Operator Product Table 33. AT&T Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Table 34. AT&T Recent Development Table 35. Verizon Company Details Table 36. Verizon Business Overview Table 37. Verizon Mobile Network Operator Product Table 38. Verizon Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Table 39. Verizon Recent Development Table 40. T-mobile Company Details Table 41. T-mobile Business Overview Table 42. T-mobile Mobile Network Operator Product Table 43. T-mobile Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Table 44. T-mobile Recent Development Table 45. Sprint Company Details Table 46. Sprint Business Overview Table 47. Sprint Mobile Network Operator Product Table 48. Sprint Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Table 49. Sprint Recent Development Table 50. China Telecom Company Details Table 51. China Telecom Business Overview Table 52. China Telecom Mobile Network Operator Product Table 53. China Telecom Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Table 54. China Telecom Recent Development Table 55. China Unicom Company Details Table 56. China Unicom Business Overview Table 57. China Unicom Mobile Network Operator Product Table 58. China Unicom Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Table 59. China Unicom Recent Development Table 60. China Mobile Company Details Table 61. China Mobile Business Overview Table 62. China Mobile Mobile Network Operator Product Table 63. China Mobile Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Table 64. China Mobile Recent Development Table 65. Telefónica Company Details Table 66. Telefónica Business Overview Table 67. Telefónica Mobile Network Operator Product Table 68. Telefónica Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Table 69. Telefónica Recent Development Table 70. Vodafone Company Details Table 71. Vodafone Business Overview Table 72. Vodafone Mobile Network Operator Product Table 73. Vodafone Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Table 74. Vodafone Recent Development Table 75. British Telecom Company Details Table 76. British Telecom Business Overview Table 77. British Telecom Mobile Network Operator Product Table 78. British Telecom Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Table 79. British Telecom Recent Development Table 80. Deutsche Telekom AG Company Details Table 81. Deutsche Telekom AG Business Overview Table 82. Deutsche Telekom AG Mobile Network Operator Product Table 83. Deutsche Telekom AG Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Table 84. Deutsche Telekom AG Recent Development Table 85. SK Telecom Company Details Table 86. SK Telecom Business Overview Table 87. SK Telecom Mobile Network Operator Product Table 88. SK Telecom Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Table 89. SK Telecom Recent Development Table 90. KT Corporation Company Details Table 91. KT Corporation Business Overview Table 92. KT Corporation Mobile Network Operator Product Table 93. KT Corporation Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Table 94. KT Corporation Recent Development Table 95. Orange Company Details Table 96. Orange Business Overview Table 97. Orange Mobile Network Operator Product Table 98. Orange Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Table 99. Orange Recent Development Table 100. NTT Docomo Company Details Table 101. NTT Docomo Business Overview Table 102. NTT Docomo Mobile Network Operator Product Table 103. NTT Docomo Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Table 104. NTT Docomo Recent Development Table 105. Softbank Company Details Table 106. Softbank Business Overview Table 107. Softbank Mobile Network Operator Product Table 108. Softbank Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Table 109. Softbank Recent Development Table 110. Jio Company Details Table 111. Jio Business Overview Table 112. Jio Mobile Network Operator Product Table 113. Jio Revenue in Mobile Network Operator Business (2017-2022) & (US$ Million) Table 114. Jio Recent Development Table 115. Research Programs/Design for This Report Table 116. Key Data Information from Secondary Sources Table 117. Key Data Information from Primary Sources List of Figures Figure 1. Mobile Network Operator Product Picture Figure 2. Global Mobile Network Operator Market Size, (US$ Million), 2017 VS 2022 VS 2028 Figure 3. Global Mobile Network Operator Market Size 2017-2028 (US$ Million) Figure 4. United States Mobile Network Operator Market Size, (US$ Million), 2017 VS 2022 VS 2028 Figure 5. United States Mobile Network Operator Market Size 2017-2028 (US$ Million) Figure 6. United States Mobile Network Operator Market Share in Global 2017-2028 Figure 7. Mobile Network Operator Report Years Considered Figure 8. Product Picture of GPRS Figure 9. Product Picture of 3G Figure 10. Product Picture of 4G/LTE Figure 11. Product Picture of 5G Figure 12. Global Mobile Network Operator Market Share by Type in 2022 & 2028 Figure 13. Global Mobile Network Operator Market Size by Type (2017-2028) & (US$ Million) Figure 14. Global Mobile Network Operator Market Share by Type (2017-2028) Figure 15. United States Mobile Network Operator Market Share by Type in 2022 & 2028 Figure 16. United States Mobile Network Operator Market Size by Type (2017-2028) & (US$ Million) Figure 17. United States Mobile Network Operator Market Share by Type (2017-2028) Figure 18. Product Picture of Mobile Phones Figure 19. Product Picture of Household Computers Figure 20. Product Picture of Smart Homes / IoT Device Figure 21. Product Picture of Enterprise Server Figure 22. Product Picture of Others Figure 23. Global Mobile Network Operator Market Share by Application in 2022 & 2028 Figure 24. Global Mobile Network Operator Market Size by Application (2017-2028) & (US$ Million) Figure 25. Global Mobile Network Operator Market Share by Application (2017-2028) Figure 26. United States Mobile Network Operator Market Share by Application in 2022 & 2028 Figure 27. United States Mobile Network Operator Market Size by Application (2017-2028) & (US$ Million) Figure 28. United States Mobile Network Operator Market Share by Application (2017-2028) Figure 29. North America Mobile Network Operator Market Size Growth Rate 2017-2028 (US$ Million) Figure 30. United States Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 31. Canada Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 32. Europe Mobile Network Operator Market Size Growth Rate 2017-2028 (US$ Million) Figure 33. Germany Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 34. France Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 35. U.K. Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 36. Italy Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 37. Russia Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 38. Asia-Pacific Mobile Network Operator Market Size Growth Rate 2017-2028 (US$ Million) Figure 39. China Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 40. Japan Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 41. South Korea Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 42. India Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 43. Australia Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 44. China Taiwan Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 45. Indonesia Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 46. Thailand Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 47. Malaysia Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 48. Latin America Mobile Network Operator Market Size Growth Rate 2017-2028 (US$ Million) Figure 49. Mexico Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 50. Brazil Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 51. Argentina Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 52. Middle East & Africa Mobile Network Operator Market Size Growth Rate 2017-2028 (US$ Million) Figure 53. Turkey Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 54. Saudi Arabia Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 55. UAE Mobile Network Operator Market Size Growth Rate (2017-2028) & (US$ Million) Figure 56. AT&T Revenue Growth Rate in Mobile Network Operator Business (2017-2022) Figure 57. Verizon Revenue Growth Rate in Mobile Network Operator Business (2017-2022) Figure 58. T-mobile Revenue Growth Rate in Mobile Network Operator Business (2017-2022) Figure 59. Sprint Revenue Growth Rate in Mobile Network Operator Business (2017-2022) Figure 60. China Telecom Revenue Growth Rate in Mobile Network Operator Business (2017-2022) Figure 61. China Unicom Revenue Growth Rate in Mobile Network Operator Business (2017-2022) Figure 62. China Mobile Revenue Growth Rate in Mobile Network Operator Business (2017-2022) Figure 63. Telefónica Revenue Growth Rate in Mobile Network Operator Business (2017-2022) Figure 64. Vodafone Revenue Growth Rate in Mobile Network Operator Business (2017-2022) Figure 65. British Telecom Revenue Growth Rate in Mobile Network Operator Business (2017-2022) Figure 66. Deutsche Telekom AG Revenue Growth Rate in Mobile Network Operator Business (2017-2022) Figure 67. SK Telecom Revenue Growth Rate in Mobile Network Operator Business (2017-2022) Figure 68. KT Corporation Revenue Growth Rate in Mobile Network Operator Business (2017-2022) Figure 69. Orange Revenue Growth Rate in Mobile Network Operator Business (2017-2022) Figure 70. NTT Docomo Revenue Growth Rate in Mobile Network Operator Business (2017-2022) Figure 71. Softbank Revenue Growth Rate in Mobile Network Operator Business (2017-2022) Figure 72. Jio Revenue Growth Rate in Mobile Network Operator Business (2017-2022) Figure 73. Bottom-up and Top-down Approaches for This Report Figure 74. Data Triangulation Figure 75. Key Executives Interviewed

AT&T Verizon T-mobile Sprint China Telecom China Unicom China Mobile Telefónica Vodafone British Telecom Deutsche Telekom AG SK Telecom KT Corporation Orange NTT Docomo Softbank Jio