| Ruthven Telephone Exchange Company | - | Graettinger, IA | Inactive |
| Rye Tel. Co. Inc. | Rye Telephone Co. | Colorado City, CO | Active |
| S & A Telephone Company, Inc. | - | Allen, KS | Active |
| S & T Tel. Coop. Assn. | S & T Telephone Cooperative Association, Inc. | Brewster, KS | Active |
| S & W Telephone Company | S & W Telephone Company, Inc. | Madison, WI | Active |
| SEI Rural Telephone Cooperative | SEI Rural Telephone Cooperative, Inc. | Dillsboro, IN | Active |
| SRT Communications, Inc. | - | Minot, ND | Active |
| Sac County Mutual Tel. Co. | Sac County Mutual Telephone Company | Odebolt, IA | Active |
| Saco River Telephone LLC | - | Oneonta, AL | Active |
| Sacred Heart Tel. Co. | Sacred Heart Telephone Company | Willmar, MN | Active |
| Sacred Wind Communications, Inc. | - | Albuquerque, NM | Active |
| Saddleback Communications | - | Scottsdale, AZ | Active |
| Salem Telephone Company | TDS Telecom | Madison, WI | Active |
| Salina-Spavinaw Tel. Co. | Salina Spavinaw Telephone Co. Inc. | Tulsa, OK | Active |
| Saluda Mountain Telephone Company | RiverStreet Networks | Wilkesboro, NC | Active |
| San Carlos Apache Telecommunications Utility, Inc. | - | Peridot, AZ | Active |
| Sand Creek Telephone Company | - | Sand Creek, MI | Active |
| Sandhill Telephone Cooperative, Inc. | - | Jefferson, SC | Active |
| Sandwich Isles Communications, Inc. | - | Mililani, HI | Active |
| Santa Rosa Telephone Cooperative, Inc. | - | Vernon, TX | Active |
| Santel Communications Cooperative, Incorprated | Santel Communications Cooperative, Inc | Woonsocket, SD | Active |
| Sawtooth Telephone, Inc. | - | Midvale, ID | Inactive |
| Scandinavia Telephone Company | TDS Telecom | Madison, WI | Active |
| Schaller Tel. Co. | Schaller Telephone Company | Schaller, IA | Active |
| Scio Mutual Telephone Association | - | Scio, OR | Active |
| Scott County Tel. Coop. | Scott County Telephone Cooperative | Gate City, VA | Active |
| Scott County Telephone Company, LLC | Scott County Telephone Company | Avilla, MO | Active |
| Scott Rice Tel. Co. | Integra Telecom | New Ulm, MN | Active |
| Scranton Tel. Co. | Scranton Telephone Company | Scranton, IA | Active |
| Searsboro Tel. Co. Inc. | Searsboro Telephone Company | Sully, IA | Active |
| Seneca Tel. Co. | Seneca Telephone Company | Seneca, MO | Active |
| Service Telephone Co. | RiverStreet Networks | Wilkesboro, NC | Active |
| Sharon Tel. Co. | Sharon Telephone Company | Sharon, WI | Active |
| Sharon Telephone Company | - | Hills, IA | Active |
| Shawnee Tel. Co. | Shawnee Telephone Company | Equality, IL | Active |
| Shell Rock Communication, Inc. | - | Plainfield, IA | Inactive |
| Shell Rock Tel. Co. | BEVCOMM | Blue Earth, MN | Inactive |
| Shenandoah Telephone Company | - | Edinburg, VA | Active |
| Sherburne County Rural Telephone Co. | SCRTC | Big Lake, MN | Inactive |
| Sherwood Mutual Tel. Assn. Inc. | Sherwood Mutual Telephone Association, Inc. | Sherwood, OH | Active |
| Shiawassee Telephone Company | TDS Telecom | Madison, WI | Active |
| Shidler Tel. Co. | Shidler Telephone Company | Shidler, OK | Inactive |
| Shoreham Telephone, LLC | - | Oneonta, AL | Active |
| Sidney Telephone Company | - | Mattoon, IL | Active |
| Sierra Tel. Co. Inc. | Sierra Telephone Company, Inc. | Oakhurst, CA | Active |
| Silver Star Telephone Co., Inc. | Silver Star Communications | Freedom, WY | Active |
| Sioux Valley Tel. Co. | Sioux Valley Telephone Company | Dell Rapids, SD | Inactive |
| Siren Tel. Co. Inc. | Siren Telephone Company | Siren, WI | Active |
| Siskiyou Tel. Co. | Siskiyou Telephone Company | Etna, CA | Active |
| Skyline Tel. Membership Corp. | Skyline Telephone Membership Corporation | West Jefferson, NC | Active |