| Business | Phone |
| Marketing Installation Systems 8170 Claiborne Dr, Frederick 21702 | (301) 620-2465 |
| Netco Inc 225 Bucheimer Rd, Frederick 21701 | (301) 668-1616 |
| Tel Data Communications Inc Frederick 21701 | (301) 663-0747 |
| Trinity Video Communications 6126 Springwater Pl # M, Frederick 21701 | (301) 668-2701 |