| CoID | Company | Type | Status | States Served | 24X7 Phone |
| TSL | Ahoy Telecom LLC | VoIP Provider | A | USA - Nationwide | 540-328-1300 |
| TSN | TerreStar Networks, Inc. (CANCELLED) | Wireless/Cellular/PCS; Satellite | C | US | 972-535-3800 |
| TSP | TeleSpace LLC | VoIP Reseller | A | USA - Nationwide | 888-988-0887 |
| TSS | TSS Digital Services Inc. - CANCELLED | CLEC Facility | VoIP | C | WA | 360-915-1000 |
| TSTR | TerreStar Networks - CANCELLED | Wireless/Cellular/PCS | C | USA | 877-667-7876 |
| TSW1 | TeraSwitch Inc. | VoIP Reseller | A | PA | 412-945-7045 |
| TTC | Tonica Telephone Co | CLEC Facility | A | IL | 815-442-9931 |
| TTCC | Tarrytech Computer Consultants | PBX/PS911/Shared Tenant VoIP Reseller VoIP Provider | A | CT | FL | NJ | NY | PA | TX | 914-432-3056 |
| TTCO | Transtelco Inc | CLEC Facility | VoIP Provider | A | | 915-534-8105 |
| TTCOK | Terral Telephone Company - CANCELLED | 9-1-1 Admin-CPE ALI | C | USA | 888-777-0390 |
| TTDWT | TidalWave Telephone, Inc. (Cancelled) | Facility | C | Maryland, Washington DC, Virginia | 703-968-5744 |
| TTE | Tallahassee Telephone Exchange, Inc. (INACTIVE) | Facility | C | FL, GA | 850-445-7069 |
| TTECH | Teletech Communications Inc. | VoIP Reseller | A | USA - Nationwide | 630-775-0200 |
| TTL | Timmins Technologies, LLC (Cancelled) | VoIP | C | All States | 866-591-0311 |
| TTNK | Titonka Telephone Company | ILEC | A | IA | 515-928-2110 |
| TTSD | Tigard Tualatin School District dialtone by Verizon - CANCELLED | PBX/PS911/Shared Tenant | C | OR | 503-431-4000 |
| TTTC | Table Top Telephone Co. Inc. | Facility | A | AZ | 520-387-5676 |
| TTU1 | Tennessee Tech University | 9-1-1 Admin-CPE ALI (9-1-1 Jurisdiction/PSAP ONLY) PBX/PS911/Shared Tenant | A | TN | 931-267-1001 |
| TUC | Daystar Communications - CANCELLED | CLEC Facility | CLEC Reseller | CLEC UNE | C | FL | 877-912-1300 |
| TUFON | Tufone, Inc. (CANCELLED) | VoIP | C | All States | 347-239-2136 |
| TULA | Salish Networks | CLEC Facility PBX/PS911/Shared Tenant VoIP Provider | A | WA | 360-716-8000 |
| TURK | Turkana LLC | VoIP Provider | A | USA - Nationwide | 415-988-2599 |
| TURN | Central Voice & Data LLC dba Turner Teleco-Alexandria | VoIP Provider | A | USA - Nationwide Louisiana | 318-442-5743 |
| TUS | Telspirion USA LLC(formerly Tiagris) - CANCELLED | CLEC Facillity | CLEC Reseller | VoIP | C | TX | 956-657-4000 |
| TUTHL | Tuthill Corporation (INACTIVE) | Facility | C | IL | 630-382-4900 |
| TVFCL | TVF Cloud Inc | VoIP Provider | A | USA - Nationwide | 407-982-7957 |
| TVH | 3 Rivers Wireless (CANCELLED) | Wireless | C | MT | 406-467-3748 |
| TVHS | The Villages Health System | PBX/PS911/Shared Tenant | A | FL | 352-751-8000 |
| TVOIP | Lumen - CenturyLink | VoIP Provider | A | USA - Nationwide | 800 357-0911 |
| TVS | One Rign Networks (Telenational Communications ) | VoIP Provider | A | AZ | CA | GA | MD | TX | 214-382-9990 |
| TVSOC | Think VoIP Services | PBX/PS911/Shared Tenant VoIP Reseller VoIP Provider | A | USA - Nationwide | 352-789-6043 x27 |
| TVSRV | TV Service Inc. | CLEC Facility | VoIP | A | KY | 606-785-3450 |
| TWBRK | Twinbrook - CANCELLED | ILEC | C | MD | 301-319-0579 |
| TWC | TelWare Corporation | VoIP Reseller | A | GA | NC | SC | VA | 800-637-3148 |
| TWCBL | Charter Fiberlink DBA Time Warner Cable (Now Charter Comm.) | Cable Digital | A | USA - Nation Wide | 844-612-9261 |
| TWCIS | Time Warner Cable Information Svcs (Cancelled - See TWCBL) | VoIP | C | nationwide | 877-777-2263 |
| TWCNC | Time Warner Cable/Raleigh | PBX/PS911/Shared Tenant | A | NC | 919-573-7190 |
| TWCOM | Lumen - CenturyLink | CLEC Facility | A | USA - Nationwide | 800 357-0911 |
| TWCSK | Twincraft Inc. | PBX/PS911/Shared Tenant | A | VT | 802-238-8661 |
| TWEST | Time Warner Telecom (Cancelled - See TWCOM) | Facility | C | WA, OR, CA, AZ, ID, NM | 800-875-9489 |
| TWG | TechWorks Group | VoIP Reseller | A | USA - Nationwide | 703-337-7777 |
| TWI | Twilio | Other - (must identify below) | non-interconnected VoIP | A | USA - Nation Wide | 855-232-9996 |
| TWIST | Twister Communications Network Inc (Cancelled) | facility | C | ALL | 800-894-7837 |
| TWNVT | Twin Valley Communications Inc | CLEC Facility | A | KS | 800-248-3631 |
| TWST | Tel West Network Services - CANCELLED | CLEC Facility | CLEC Reseller | CLEC UNE | C | TX | 800-813-3880 |
| TWT | Tidewater Telecom/Lincolnville Tel. | ILEC | A | ME | 207-563-9931 |
| TWTIN | Telewebtech | VoIP Reseller | A | USA - Nationwide | 317-439-6697 |
| TWU | Texas Womans's University | PBX/PS911/Shared Tenant | A | TX | 940-368-3438 |
| TWVLY | Twin Valley Telephone Inc | ILEC | A | KS | 800-248-3631 |
| TXACQ | TX11 Acquisition LLC dba Cellular One - CANCELLED | Wireless/Cellular/PCS | C | TX | 936-590-1568 |