| CoID | Company | Type | Status | States Served | 24X7 Phone |
|---|---|---|---|---|---|
| UNDP | United Nations Development Programme | Other - (must identify below) | Non profit International Organization | A | NY | 212-906-5000 |
| UNHQ | United Nations - CANCELLED | PBX/PS911/Shared Tenant | C | NJ | NY | 212-963-6666 |
| UNIFI | Unified Telecom Inc. DBA CCSi Communications | VoIP Reseller VoIP Provider | A | USA - Nationwide | 630-241-0600 |
| UNIMT | Univision Inc. | VoIP Reseller | A | USA - Nationwide | 406-721-8876 |
| UNION | Union Telephone Company | ILEC Wireless/Cellular/PCS VoIP Provider | A | WY | 307-782-6131 |
| UNITS | The Ohio State University | PBX/PS911/Shared Tenant | A | OH | 614-292-2525 |
| UNITY | Unitel Inc | CLEC Facility ILEC VoIP Provider | A | ME | 207-948-5757 |
| UNIV | Oahu Transit Services Inc - CANCELLED | UNIV | C | HI | 877-374-4530 |
| UNL | Broadwing Local Services Inc. (Cancelled) | Reseller | C | OH, IN, KY | 800-735-3030 |
| UNRV | Union River Telephone Company | ILEC | A | ME | 207-944-9279 |
| UNTEL | United Telephone Association Inc. | ILEC | A | KS | OK | 620-471-4338 |
| UNWLS | United Wireless Communications Inc. | Wireless/Cellular/PCS | A | KS | 620-471-4338 |
| UO-UO | Unified Office Inc | VoIP Provider | A | USA - Nation Wide | 603-427-9500 |
| UOFID | University of Idaho - CANCELLED | PBX/PS911/Shared Tenant | C | ID | 208-885-6111 |
| UofR | University of Rochester | PBX/PS911/Shared Tenant | A | NY | 585-756-4800 |
| UOP | University of the Pacific - CANCELLED | PBX/PS911/Shared Tenant | C | CA | 209-946-3968 |
| UOR | University of Redlands | PBX/PS911/Shared Tenant | A | CA | 909-748-8888 |
| UPCOM | Uplink Communications LLC - CANCELLED | VoIP Reseller | C | MS | 888-551-9296 |
| UPENN | University of Pennsylvania | PBX/PS911/Shared Tenant VoIP Provider | A | PA | 215-746-7924 |
| UPHP | Peninsula Fiber Network LLC | CLEC Facility | A | MI | 906-226-2010 |
| UPMGH | Peninsula Fiber Network LLC | CLEC Facility | A | MI | 906-226-2010 |
| UPN | Unite Private Networks | CLEC Facility PBX/PS911/Shared Tenant VoIP Reseller VoIP Provider | A | USA - Nationwide | 866-963-4327 |
| UPRTE | Uprite Services | CLEC Reseller VoIP Provider | A | TX | 281-956-2270 |
| UPS | Upsala Cooperative Telephone Ass'n | Facility | A | MN | 320-630-8057 |
| UPTEL | Upper Peninsula Telephone Company | CLEC | A | MI | 906-639-2110 |
| URBAN | Urban Media (Out of Business) | Facility | C | ALL | 888-648-5662 |
| URI | University of Rhode Island | VoIP | A | URI-Kingston Campus/Bay Campus | 401-874-2121 |
| URICH | University of Richmond | A | VA | 804-289-8715 | |
| USA | USA Telephone Inc. (CANCELLED) | Reseller | C | FL | 305-944-8383 |
| USACV | Vanu Coverage Co Inc. - CANCELLED | Wireless/Cellular/PCS | C | VT | 617-864-1711 |
| USAD | USA Digital Communications Inc. | VoIP Provider | A | USA - Nation Wide | 888-872-3787 |
| USANE | Telemetrix Inc - CANCELLED | Wireless/Celluar/PCS | C | NE | 303-517-1933 |
| USAT | United Systems Access Telecom Inc. - CANCELLED | Facility | C | ME | 207-851-0564 |
| USAVC | Medical Management of Chicago DBA USA Vein Clinics | PBX/PS911/Shared Tenant | A | USA - Nationwide | 224-318-0118 |
| USBRO | US BANK | PBX/PS911/Shared Tenant | A | USA - Nationwide | 651-312-4810 |
| USCA | Novartis Institute of BioMedical Research Inc (INACTIVE) | PBX | C | MA | 617-871-4444 |
| USCC | US Cellular Corporation | Wireless/Cellular/PCS | A | CA | IL | IN | IA | KS | ME | MD | MI | MN | MO | NE.NH | NY | NC | OK | OR | PA | SC | TN | TX | VT | VA | WA | WV | WI | 630-875-8270 - 1 |
| USCG | United States Coast Guard(Cancelled) | PBX/PS911/Shared Tenant | C | DC | 202-372-4290 |
| USD | University of San Diego | VoIP Reseller | A | CA | 877-441-0990 |
| USDB | Utah Schools for the Deaf and the Blind | PBX/PS911/Shared Tenant | A | UT | 801-710-7427 |
| USDC | U.S. District Court, Clerk's Office (Cancelled) | PBX | C | U.S. Courthouse 601 Market Street | 215-597-7704 |
| USDOI | US Department of the Interior - CANCELLED | PBX/PS911/Shared Tenant | C | DC | 480-719-8556 |
| USDOT | US Department of Transportation - CANCELLED | PBX/PS911/Shared Tenant | C | DC | 202-366-0333 |
| USEPA | United States Environmental Protection Agency (Cancelled) | VoIP | C | VA, DC | 703-347-8707 |
| USF | University of South Florida - CANCELLED | PBX/PS911/Shared Tenant | C | FL | 800-333-9873 |
| USFPS | University Of San Francisco | PBX/PS911/Shared Tenant | A | CA | 415-422-4201 |
| USGS | US Geological Survey - CANCELLED | 9-1-1 Admin-CPE ALI (9-1-1 Jurisdiction/PSAP ONLY) | C | USA - Nationwide | 703-648-7036 |
| USI | US Internet Corp | VoIP Provider | A | USA | 866-728-6676 |
| USIPC | USIPCOM | VoIP Provider | A | USA - Nation Wide | 800-972-5004 |
| USIT | US In Touch (CANCELLED) | Facility | C | NV | 775-513-2831 |