| Skyline Telecom | - | Fairview, UT | Active |
| Sledge Tel. Co. Inc. | Sledge Telephone Co. | Sunflower, MS | Active |
| Sleepy Eye Telephone Company | - | New Ulm, MN | Active |
| Smart City Telecommunications, LLC | Smart City Telecom | Lake Buena Vista, FL | Active |
| Smithville Communications, Inc. | - | Ellettsville, IN | Active |
| Smithville Telephone Co, Inc. | Smithville Telephone Company, Inc. | Smithville, MS | Active |
| Sodtown Tel. Co. | Sodtown Telephone Company | Ravenna, NE | Active |
| Somerset Tel. Co. Inc. | Somerset Telephone Co., Inc. | Amery, WI | Active |
| Somerset Telephone Company | TDS Telecom | Madison, WI | Active |
| South Arkansas Telephone Company | - | Sheridan, AR | Active |
| South Canaan Telephone Company | The South Canaan Telephone Company | South Canaan, PA | Inactive |
| South Canaan Telephone Company | - | Stahlstown, PA | Active |
| South Central Communications, Inc. | SCC Networks | Princeton, MO | Active |
| South Central Rural Tel. Coop. Corp. Inc. | South Central Rural Telephone Cooperative Corp Inc | Glasgow, KY | Active |
| South Central Telecommunications Of Kiowa, Inc | South Central Telecommunications of Kiowa, Inc. | Medicine Lodge, KS | Active |
| South Central Telephone Association - KS | - | Medicine Lodge, KS | Active |
| South Park, LLC | South Park Telephone Company | Colorado City, CO | Active |
| South Plains Tel. Coop. Inc. | South Plains Telephone Cooperative, Inc. | Lubbock, TX | Active |
| South Slope Cooperative Telephone Co. Inc. | South Slope Cooperative Telephone Company | North Liberty, IA | Active |
| Southeast Mississippi Telephone Company | TDS Telecom | Madison, WI | Active |
| Southeast Nebraska Communications, Inc | - | Falls City, NE | Active |
| Southeast Telephone Company of Wisconsin, Inc. | TDS Telecom | Madison, WI | Active |
| Southern Kansas Tel. Co. Inc. | Southern Kansas Telephone Co., Inc. | Clearwater, KS | Active |
| Southern Montana Tel. Co. | Southern Montana Telephone Co. | Wisdom, MT | Active |
| Southwest Arkansas Tel. Coop. Inc. | Southwest Arkansas Telephone Cooperative, Inc. | Texarkana, AR | Active |
| Southwest Oklahoma Tel. Co. | - | Duke, OK | Active |
| Southwest Telephone Exchange | Southwest Telephone Exchange, Inc. | Truro, IA | Inactive |
| Southwest Texas Tel. Co. | Southwest Texas Telephone Company | Rocksprings, TX | Active |
| Southwestern Bell Telephone Company | AT&T Southwest | Dallas, TX | Active |
| Southwestern Telephone Company | TDS Telecom | Madison, WI | Active |
| Spectra Communications Group, LLC | - | Monroe, LA | Active |
| Splitrock Properties Inc. | Splitrock Properties, Inc. | Garretson, SD | Inactive |
| Spring Grove Communications | - | Spring Grove, MN | Active |
| Spring Valley Tel. Co. Inc. | Spring Valley Telephone Company, Inc. | Spring Valley, WI | Active |
| Springport Tel. Co. | Springport Telephone Company | Springport, MI | Active |
| Springville Coop. Tel. Assn. Inc. | Springville Cooperative Telephone Association, Inc | Springville, IA | Active |
| Sprint - Florida, Inc | Sprint Florida, Inc. | Overland Park, KS | Inactive |
| Sprint - Missouri, Inc | Sprint Missouri, Inc | Overland Park, KS | Inactive |
| Sprint- Minnesota, Inc. | Sprint Minnesota, Inc. | Westwood, KS | Inactive |
| Sprint/Carolina Telephone & Telegraph Co. | Sprint/ Carolina Telephone and Telegraph Company - | Overland Park, KS | Inactive |
| Sprint/Central Tel. Co. - Nevada | Sprint/ Central Telephone Company - Nevada | Westwood, KS | Inactive |
| Sprint/Central Telephone Company - North Carolina | Sprint/ Central Telephone of North Carolina | Overland Park, KS | Inactive |
| Sprint/Central Telephone Company of Texas | Sprint/ Central Telephone Company of Texas | Overland Park, KS | Inactive |
| Sprint/Central Telephone Company of Virginia | Sprint/ Central Telephone Company of Virginia | Overland Park, KS | Inactive |
| Sprint/United Tel. - Southeast, Inc. | United Telephone - Southeast, Inc. | Overland Park, KS | Inactive |
| Sprint/United Tel. Co. of Kansas | Sprint/ United Telephone Company of Kansas | Overland Park, KS | Inactive |
| Sprint/United Tel. Co. of Pennsylvania | Sprint/ United Telephone Company of Pennsylvania | Overland Park, KS | Inactive |
| Sprint/United Tel. Co. of the Carolinas | Sprint/ United Telephone Company of the Carolinas | Overland Park, KS | Inactive |
| Sprint/United Telephone - Northwest | United Telephone - Northwest | Overland Park, KS | Inactive |
| Sprint/United Telephone Company of Eastern Kansas | Sprint/ United Telephone Company of Eastern Kansas | Overland Park, KS | Inactive |