| Business | Phone |
| Acc Telecom Corp 6410 Dobbin Rd # A, Columbia 21045 | (410) 995-0101 |
| Consultel 6547 Cedar Ln, Columbia 21044 | (410) 531-2700 |
| Convergent Communications 8310 Guilford Rd, Columbia 21046 | (410) 720-6400 |
| Dcm Communications 6760 Alexander Bell Dr, Columbia 21046 | (410) 720-6262 |
| Perfect Phone Corp 9140 Guilford Rd # C, Columbia 21046 | (410) 792-2250 |
| Regional Telecommunications 10103 Windstream Dr, Columbia 21044 | (410) 995-1688 |
| Simply Wireless Inc 10300 Little Patuxent Pkwy, Columbia 21044 | (410) 964-9400 |
| Tecore 7165 Columbia Gateway Dr, Columbia 21046 | (410) 872-6000 |
| Third Generation Of Maryland 9800 Patuxent Woods Dr, Columbia 21046 | (410) 312-9727 |
| Trinity Telecom 9515 Gerwig Ln # 102, Columbia 21046 | (410) 290-5200 |