| Hooper Telephone Company dba WesTel Systems | Hooper Telephone Company | Remsen, IA | Active |
| Hopi Telecommunications, Inc. | - | Flagstaff, AZ | Active |
| Hopper Telecommunications LLC | - | Oneonta, AL | Active |
| Hornitos Tel. Co. dba TDS Telecom | TDS Telecom | Madison, WI | Active |
| Horry Telephone Cooperative, Inc. | - | Conway, SC | Active |
| Hospers Tel. Exch. Inc. | HTC Communications | Sioux Center, IA | Active |
| Hot Springs Tel. Co. | Hot Springs Telephone Company | MISSOULA, MT | Active |
| Hubbard Coop. Tel. Assn. | Hubbard Cooperative Telephone Association | Hubbard, IA | Active |
| Humphreys County Tel. | TDS Telecom | Madison, WI | Active |
| Hutchinson Tel. Co. | Hutchinson Telephone Company | New Ulm, MN | Active |
| Huxley Communications Cooperative | Huxley Communications | Huxley, IA | Active |
| IAMO Telephone Company | - | Coin, IA | Active |
| ITS Telecommunications Systems Inc. | - | Indiantown, FL | Active |
| Illinois Bell Telephone Company | AT&T Illinois | Chicago, IL | Active |
| Indiana Bell Telephone Company, Incorporated | AT&T Indiana | Indianapolis, IN | Active |
| Indianhead Tel. Co. | Indianhead Telephone Company | Blue Earth, MN | Active |
| Industry Tel. Co. | Industry Telephone Company | Industry, TX | Active |
| Inland Telephone Company | - | Roslyn, WA | Active |
| Inter-Community Telephone Company | - | Steele, ND | Active |
| Inter-Community Telephone Company II | - | Nome, ND | Inactive |
| Interbel Telephone Cooperative, Inc. | - | Eureka, MT | Active |
| Interior Telephone Company | - | Anchorage, AK | Active |
| Interstate 35 Tel. Co. | Interstate 35 Telephone Company | Truro, IA | Inactive |
| Interstate Telecommunications Coop., Inc. | Interstate Telecom | Clear Lake, SD | Active |
| Ironton Telephone Company | - | Coplay, PA | Active |
| J.B.N. Telephone Company | JBN Telephone Co., Inc. | Holton, KS | Active |
| JED Enterprises, Inc. dba Pine Drive Telephone Co. | Pine Drive Telephone Company | Beulah, CO | Active |
| James Valley Cooperative Tel. Co. | James Valley Telecommunications | Groton, SD | Active |
| Jefferson Telephone Company | Jefferson Telecom | Jefferson, IA | Active |
| Jefferson Telephone Company, LLC | Jefferson Telephone Company, Inc. | Sergeant Bluff, IA | Active |
| Johnson Tel. Co. | Johnson Telephone Company | Remer, MN | Active |
| Jordan-Soldier Valley Telephone Company | - | Sergeant Bluff, IA | Active |
| K & M Telephone Company, Inc | K&M Telephone Company, Inc. | Chambers, NE | Active |
| K L M Telephone Company | KLM Telephone Company | Blair, NE | Active |
| KNOLOGY OF THE VALLEY, INC. | KNOLOGY OF THE VALLEY, INC | West Point, GA | Active |
| Kadoka Tel. Co., Inc | Kadoka Telephone Company | Dell Rapids, SD | Inactive |
| Kalama Tel. Co. | Kalama Telephone Company | Tenino, WA | Active |
| Kaleva Telephone Co. | Kaleva Telephone Company | Kaleva, MI | Active |
| Kalida Telephone Company, Inc. | Kalida Telephone Co., Inc. | Kalida, OH | Active |
| Kalona Cooperative Telephone Company | - | Kalona, IA | Active |
| KanOkla Telephone Association | - | Caldwell, KS | Active |
| Kaplan Telephone Company, Inc. | KTC Pace | Kaplan, LA | Active |
| Kasson & Mantorville Tel. Co. | Kasson & Mantorville Telephone Company | Kasson, MN | Active |
| Kearsarge Telephone Co. | TDS Telecom | Madison, WI | Active |
| Kennebec Telephone Company | Kennebec Telephone Co., Inc. | Kennebec, SD | Active |
| Kerman Telephone Co. | Sebastian | Kerman, CA | Active |
| Keystone Farms Coop. Tel. Co. | Keystone Farmers Cooperative Telephone Company | Keystone, IA | Active |
| Killduff Telephone Company | - | Sully, IA | Active |
| Kingdom Tel. Co. | Kingdom Telephone Company | Auxvasse, MO | Active |
| Kinsman Mutual Tel. Co. | Kinsman Mutual Telephone Co. | Kinsman, IL | Active |