| Barcom, Inc. | 618-277-3344 |
| Best Engineered Systems | 618-616-0877 |
| Comm Squad | 618-624-8340 |
| Custom Communications | 618-664-3800 |
| Cannon Utilities | 618-236-2800 |
| Datatronics, Inc. | 618-463-1440 |
| Guarantee Electric | 618-452-6122 |
| J. F. Electric | 618-656-8371 |
| MAC Electric, Inc. | 618-632-6672 |
| MC Electric | 618-282-7788 |
| Pyramid Elec. (Telecom) | 618-632-1180 |
| Sachs Electric | 314-743-1189 |
| Wireless USA | 618-344-7000 |