These callboxes are left in an auto-turnoff mode so they will not receive any transmissions unless the call button is first pressed to wake them up. So every floor will not hear the communications between the worker and the operator.
What goes in the elevator car depends on whether there is power in there or not. You could just use another callbox but it would have to be taken out of the auto turnoff mode so the batteries would only last a week or so. The callbox would really need to be powered via 12 volts DC.
Another option is our Commercial Base Station. It also requires 12Volts DC. It is not weatherproof like the callbox would be. It can be mounted to the wall of the elevator.
The third option is a handheld two-way radio. The operator would wear it on his belt and he could use a headset or shoulder lapel microphone to talk to people.
There are two different frequencies this equipment is available in, either MURS or UHF. The MURS equipment does not require an FCC license but antenna height of MURS equipment is not supposed to be over 60 feet. The MURS VHF signals can also travel for many miles, so for buildings that are really high this means you could pick up interference from many miles away. So we recommend you only use this for 6 stories or less.
So in most cases we recommend UHF equipment. It does require hiring a license coordinator to get a 10 year license but in large cities that have a high amount of two-way radio traffic, this will give you a more reliable system.
If your construction elevators move around to different areas you will need what is called an "itinerant" license, which means it can travel around. These licenses don't guarantee you a clear frequency like a standard license so you may be sharing a frequency in areas. Our equipment has privacy codes that can be used along with the frequency you use so unless that code is transmitted when the call button is pressed, the speaker on the receiving device will remain turned off. A 10-year license costs $450 for multiple frequencies, and it will work for any number of devices you want.
See more info and pricing here:
UHF Construction Elevator Intercom
MURS Construction Elevator Intercom
Wired Construction Elevator Intercom
Another choice for a construction lift intercom is our wired system. Technically it operates on unlicensed wireless frequencies however it requires a power line be run from unit to unit so we consider it a wired intercom.
This system requires one power supply inside the elevator hoist that powers the intercom in it. Another power supply is mounted on the first floor and it powers all the intercoms on the other floors.