| Business | Phone |
| Atlantic Security Systems Inc 19741 Leitersburg Pike # G, Hagerstown 21742 | (301) 797-7700 |
| Cantner Alarm Svc Rr 10 Box 29g, Hagerstown 21742 | (301) 791-0677 |
| Tele-Plus Corp 916 Eldridge Dr, Hagerstown 21740 | (301) 797-9500 |
| Glessner Alarm & Comm Corp 120 W Antietam St, Hagerstown 21740 | (301) 694-8282 |
| Glessner Alarm & Comms 1216 Sherman Ave, Hagerstown 21740 | (301) 797-1280 |