| Business | Phone |
| Metropolitan Security System Po Box 387, Reisterstown 21136 | (410) 833-3725 |
| Absolute Security Po Box 984, Reisterstown 21136 | (410) 517-1077 |
| Alarm Doctor Inc 4902 Pleasant Grove Rd, Reisterstown 21136 | (410) 526-7780 |
| Antel Electronics 12630 Ivy Mill Rd, Reisterstown 21136 | (410) 526-9300 |
| Arm Security Systems Inc 208 Main St, Reisterstown 21136 | (410) 526-4990 |