| CoID | Company | Type | Status | States Served | 24X7 Phone |
| ASD16 | Arlington School District | 9-1-1 Admin-CPE ALI (9-1-1 Jurisdiction/PSAP ONLY) | A | USA - Nationwide | 360-913-7005 |
| ASI | Asset Sentinel Inc. (Out of Business) | PBX | C | USA | 612-934-2655 |
| ASPEN | Aspen Datacom (Cancelled) | Facility | C | IL | 773-878-3161 |
| ASPRS | Aspirus Wausau Hospital | Cable Digital Internet Protocol Relay Provider VoIP Provider | A | MI | WI | 715-847-2121 |
| ASSOC | Associated Bank - CANCELLED | 9-1-1 Admin-CPE ALI | C | WI | 715-345-4600 |
| ASTAC | Arctic Slope Telephone Association Coop Inc | ILEC Wireless/Cellular/PCS | A | AK | 877-751-5068 |
| ASTCO | Astro Telecommunications LLC | CLEC Facility CLEC Reseller VoIP Reseller VoIP Provider | A | USA - Nationwide | 833-462-7876 |
| ASTND | Astound Broadband LLC - CANCELLED | CLEC Facility | C | CA | OR | WA | 866-928-3123 |
| ASTRO | AstroTel, Inc. (INACTIVE) | CLEC Facility | C | FL | 877-833-2453 |
| ASU | Angelo State University - CANCELLED | VoIP Provider | C | TX | 325-942-2911 |
| ASUMP | Assumption College | PBX | A | MA | 508-767-7000 |
| AT&T | AT&T | CLEC Facility | A | USA - Nationwide | 888-249-4980 |
| ATBLS | AT&T | CLEC Reseller | A | CA | 800-275-0014 |
| ATC | Alma Telephone Company Inc. | Facility | A | GA | 912-632-5911 |
| ATC83 | Advantage Telephone Communications | VoIP Provider | A | USA - Nationwide | 281-435-6348 |
| ATCID | ATC Communications Inc. | ILEC | A | ID | 208-673-5335 |
| ATCMD | Armstrong Telephone Company - Maryland | ILEC | A | MD | 877-277-5709 |
| ATCN | Armstrong Telephone Company - North | ILEC | A | PA | 877-277-5709 |
| ATCND | Armstrong Telephone Co Northern Div. | ILEC | A | WV | 877-277-5709 |
| ATCNE | ATC Communications | ILEC | A | NE | 308-962-7298 |
| ATCNY | Armstrong Telephone Company | ILEC | A | NY | 877-277-5709 |
| ATCO | Ardmore Telephone Company Inc. | ILEC VoIP Reseller | A | AL | TN | 270-856-1033 |
| ATCPA | Armstrong Telephone Company - PA | ILEC | A | PA | 877-277-5709 |
| ATCTC | American Telephone Company | CLEC Facility CLEC Reseller VoIP Reseller VoIP Provider | A | USA - Nation Wide | 888-943-8282 |
| ATCWV | Armstrong Telephone Company - WV | ILEC | A | WV | 877-277-5709 |
| ATEL | Adams TelSystems Inc. | CLEC Facility CLEC UNE VoIP Reseller VoIP Provider | A | IL | 217-696-4411 |
| ATG | ATG Communications LLC | VoIP Reseller VoIP Provider | A | USA - Nation Wide | 706-823-1449 opt 2 |
| ATG23 | Applied Technology Group | | A | | 260-482-2844 |
| ATGCO | ATG Corp. - CANCELLED | VoIP Reseller VoIP Provider | C | USA - Nationwide | 208-906-8320 |
| ATGI | Advanced Telecom | 9-1-1 Admin-CPE ALI (9-1-1 Jurisdiction/PSAP ONLY) | PBX | A | CA | NV | OR | WA | 877-679-9432 |
| ATHER | Atheral LLC | VoIP Reseller VoIP Provider | A | USA - Nationwide | 702-470-2766 |
| ATHR | The Arthur Mutual Telephone Co. | LEC | A | OH | 419-393-2233 |
| ATI | Affinity Telecom, Inc.(Cancelled) | CLEC Faciliy, CLEC Reseller, CLEC UNE | C | CO | 303-961-0022 |
| ATIAR | Armstrong Telecommunications Inc | CLEC Facility | A | KY | MD | NY | OH | PA | WV | 877-277-5709 |
| ATIMN | ATI (Cancelled - See ESCH) | Facility | C | MN | 612-964-5794 |
| ATLAS | Atlas Electric Devices (Cancelled) | Facility | C | IL | 773-327-4520 |
| ATLC | Atlantic Telecom Multimedia Consolidated | CLEC Facility | A | NC | 910-754-1730 |
| ATMC | Atlantic Telephone Membership Corp | Co-Op/Rural ILEC | A | NC | 910-754-1730 |
| ATN | All Tel Networks LLC | VoIP Provider | A | USA - Nationwide | 772-215-1140 |
| ATS | ATS Telecommunications (Cancelled) | Facility | C | TX | 888-326-3302 |
| ATSLC | ATS Services, LLC (Cancelled) | Reseller | C | Illinois Counties: Cook, Kane, Lake, McHenry, DuPage, Will | 888-675-6347 |
| ATTBB | Insight Phone of Kentucky, LLC (CANCELLED) | Facility | C | OH | 800-771-9124 |
| ATTCS | AT&T Consumer Services, Inc (Cancelled) | CLEC Facility | C | ALL | 888-249-4980 |
| ATTI | A-Tech Telecom, Inc. (Cancelled) | UNE | C | TX,KY,AR | 972-527-2488 |
| ATTIS | AT&T | CLEC Facility ILEC VPC | A | USA - Nationwide | 877-450-1990 |
| ATTLS | AT&T | CLEC Reseller | A | CA | NV | 800-275-0014 |
| ATTMO | AT&T Mobility | Wireless/Cellular/PCS | A | USA - Nation Wide | 800-635-6840 opt. 4 |
| ATTPS | AT&T (Cancelled) | PS ALI | C | National | 888-249-4980 |
| ATTSP | AT&T Mobility | Wireless/Cellular/PCS | A | USA - Nationwide | 800-635-6840 opt. 4 |
| ATTWS | AT&T Wireless Services, Inc. (CANCELLED-See CING) | Wireless | C | ALL States | 800-635-6840 |