| California Phones LP-01 | Digital Access Communications (agent) | Payphone Service Provider | Seattle | Inactive |
| California Phones LP-02 | Digital Access Communications (agent) | Payphone Service Provider | Seattle | Inactive |
| California Phones LP-03 | Digital Access Communications (agent) | Payphone Service Provider | Seattle | Inactive |
| California Phones LP-04 | Digital Access Communications (agent) | Payphone Service Provider | Seattle | Inactive |
| California Phones LP-05 | Digital Access Communications (agent) | Payphone Service Provider | Seattle | Inactive |
| California Phones LP-06 | Digital Access Communications (agent) | Payphone Service Provider | Seattle | Inactive |
| California Phones LP-07 | Digital Access Communications (agent) | Payphone Service Provider | Seattle | Inactive |
| California Phones LP-08 | Digital Access Communications (agent) | Payphone Service Provider | Seattle | Inactive |
| California Phones LP-09 | Digital access Communications (agent) | Payphone Service Provider | Seattle | Inactive |
| California Phones LP-10 | Digital Access Communications (agent) | Payphone Service Provider | Seattle | Inactive |
| California Phones LP-11 | Digital Access Communications (agent) | Payphone Service Provider | Seattle | Inactive |
| California Phones LP-12 | Digital Access Communications (agent) | Payphone Service Provider | Seattle | Inactive |
| California Phones LP-14 | Digital Access Communications (agent) | Payphone Service Provider | Seattle | Inactive |
| California Phones LP-15 | Digital Access Communications (agent) | Payphone Service Provider | Seattle | Inactive |
| Calneva Towers | CalNeva Towers | Private Service Provider | Bellingham | Active |
| Capacity Provisioning, Inc. | - | Private Service Provider | Port Angeles | Inactive |
| Capalon Communications, Inc. | Capalon Communications | Interconnected VoIP | Spokane Valley | Active |
| Cascade Networks, Inc. | - | Wireless Data | Longview | Inactive |
| Cascade Wireless, LLC | - | Cellular/PCS/SMR | Bellevue | Inactive |
| Cedar Communications, LLC | - | CAP/CLEC | Kirkland | Inactive |
| Cellular Alaska Partnership | AT&T Wireless Services, Inc. | Cellular/PCS/SMR | Redmond | Inactive |
| Cellular Telephone Company | AT&T Wireless Services, Inc. | Cellular/PCS/SMR | Redmond | Inactive |
| Centel Communications, Inc. | - | Local Reseller | Goldendale | Inactive |
| Central Telephone, Inc. | - | Payphone Service Provider | Goldendale | Active |
| Christian Media Technologies, Inc. | - | Interexchange Carrier | Vancouver | Inactive |
| Citrus Cellular Limited Partnership | AT&T Wireless Services, Inc. | Cellular/PCS/SMR | Redmond | Inactive |
| City of Tacoma, Dept. of Public Utilities, Light D | Click! Network | CAP/CLEC | Tacoma | Active |
| Claircom Licensee Corporation | AT&T Wireless Services, Inc. | Cellular/PCS/SMR | Redmond | Inactive |
| Clantera, LLC | Cabertel | Interconnected VoIP | Redmond | Active |
| Clayton Gunst | - | Payphone Service Provider | Seattle | Inactive |
| Clearwire Telecommunications Services, LLC. | Clearwire Telecommunications Services, LLC. or Cle | CAP/CLEC | Bellevue | Inactive |
| Clearwire US, LLC. | Clearwire US, LLC or Clearwire | Interconnected VoIP | Kirkland | Inactive |
| Coast Communications Co., Inc. | - | CAP/CLEC | Ocean Shores | Active |
| Coin Telecom, Inc. | Coin Telecom | Toll Reseller | St John | Inactive |
| Cointel, Inc. | - | Payphone Service Provider | Arlington | Inactive |
| Columbia Energy, LLC | - | Wireless Data | Walla Walla | Active |
| CommandLink LLC | - | Interconnected VoIP | Everett | Active |
| Communication Lines, Inc. | - | Local Reseller | University Place | Inactive |
| Communications Management Corp. | - | Payphone Service Provider | Seattle | Inactive |
| Computer 5, Inc. | LocalTel Communications | CAP/CLEC | East Wenatchee | Active |
| Concept Communication Corporation | Concept Communication Corporation/MiFiber | Other Local | Newport | Active |
| Country Cable LLC | - | CAP/CLEC | Spokane | Active |
| Courtesy Communications | Courtesy Communications, Inc. | Paging & Messaging | Spokane | Inactive |
| Crescomm Services, Inc. | Crescomm Wireless | Paging & Messaging | Joyce | Active |
| Crescomm WIFI, LLC | Crescomm Broadband | Paging & Messaging | Long Beach | Inactive |
| Cross Stream Communications, Inc. | Cross Stream Communications | Local Reseller | Auburn | Active |
| CrossConnection, Inc. | CrossConnection, Inc | Other Toll | Renton | Inactive |
| D & E/ Omnipoint Wireless Joint Venture, LP | PCS One | Cellular/PCS/SMR | Bellevue | Inactive |
| DTMicro, Inc | - | Private Service Provider | Bremerton | Active |
| Dallas Mobile Communications Partnership | - | SMR (dispatch) | Mukilteo | Active |