| CoID | Company | Type | Status | States Served | 24X7 Phone |
| APEIR | Apeiron Systems Inc. | VoIP Provider | A | USA - Nation Wide | 310-705-0050 |
| APHRD | USDA APHIS - CANCELLED | 9-1-1 Admin-CPE ALI | C | MD | 301-672-0907 |
| API | Access Point Inc. | Cable Digital CLEC Facility CLEC Reseller CLEC UNE PBX/PS911/Shared Tenant VoIP Provider | A | USA - Nation Wide | 877-419-4274 |
| APL | Johns Hopkins University Applied Physics Laboratory (JHUAPL) | Other | Company Internal MLTS | A | MD | VA | 240-228-3333 |
| APOG | Apogee Telecom (CANCELLED) | Reseller | C | TX | 888-245-0608 |
| APOLO | Apollo Group, Inc. (CANCELLED) | PBX/PS911/Shared Tenant | C | USA | 602-557-6600 |
| APS | Alpena Public School District | 9-1-1 Admin-CPE ALI (9-1-1 Jurisdiction/PSAP ONLY) | A | MI | 989-358-5200 |
| APSD | Alpena Public School District(Cancelled) | PBX/PS911/Shared Tenant | C | MI | 800-773-7911 |
| APTAK | AP&T Wireless | ILEC PBX/PS911/Shared Tenant VoIP Reseller VoIP Provider | A | AK | 907-903-3085 |
| APU | Azusa Pacific University - CANCELLED | PBX/PS911/Shared Tenant | C | CA | 626-815-3898 |
| APW | Altmar Parish Williamstown Central School District | Other | PS/ALI or Private Switch | A | NY | 800-773-7911 |
| AQMD | South Coast Air Quality Management District | 9-1-1 Admin-CPE ALI (9-1-1 Jurisdiction/PSAP ONLY) | A | CA | 909-718-9097 |
| ARAMK | ARAMARK Corporation - CANCELLED | PBX/PS911/Shared Tenant | C | Philadelphia | PA | 215-238-3001 |
| ARBIT | NIELSEN/ARBITRON | PBX/PS911/Shared Tenant | A | MD | 410-312-8000 |
| ARBL | Arbella Mutual Insurance Company | ILEC | A | CT | MA | 617-328-2525 |
| ARBRS | Arbros Communications, Inc. (Cancelled) | Facility | C | ALL | 877-427-2767 |
| ARC | ARC Networks dba InfoHighway Communications(Cancelled) | Reseller | C | CT | 888-272-6389 |
| ARCAD | Arcadia Telephone Cooperative - CANCELLED | ILEC | C | IA | 712-689-2238 |
| ARCOR | Antero Resources Corporation | 9-1-1 Admin-CPE ALI (9-1-1 Jurisdiction/PSAP ONLY) | A | CO | OH WV | 303-357-7310 |
| ARE | Arena One LLC | VoIP Provider | A | USA | 212-231-9600 |
| ARFRE | Airadigm Communications - CANCELLED | Wireless/Cellular/PCS | C | WI | 920-707-4357 |
| ARKDN | NTT Cloud Communications US Inc. | Video Relay Service VoIP Provider Other (must identify below) | Conference Services and Cloud Voice | A | USA - Nation Wide | 866-922-9566 |
| ARLLN | Arialink Telecom - CANCELLED | CLEC Facililty | CLEC Reseller | CLEC UNE | VoIP Reseller | VoIP Provider | C | MI | 517-492-1350 |
| ARMSE | ARCH Medical Solutions - Seabrook | PBX/PS911/Shared Tenant | A | USA - Nationwide | 603-474-1919 |
| ARMST | Armstrong Utilities (CANCELLED) | PBX | C | PA | 724-899-2211 |
| ARNG | Arkansas Army National Guard - CANCELLED | CLEC Facility | C | USA-Nation Wide AR | 501-590-5735 |
| ARNG1 | Vermont Army National Guard | PBX/PS911/Shared Tenant | A | VT | 802-338-3050 |
| ARORA | Aurora Communications Inc c/o Wisper ISP LLC - CANCELLED | CLEC Facility VoIP Provider | C | MO | 618-206-4190 |
| ARPS | Amherst Regional Public Schools | Facility | A | MA | 413-362-1810 |
| ART | Artisan Communications (CANCELLED) | VoIP | C | KS | 866-733-8878 |
| ARTCH | AirTouch Communications (Cancelled) | ILEC | C | WA, OR, ID, UT, CO, AZ, NM, NE, WY, ND, MN, IA | 800-445-5514 |
| ASCC | Asnuntuck Community College - CANCELLED | VoIP | C | CT | 413-829-1977 |
| 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 |