load control comms query

As a homeowner and electricity consumer, I received several notes on my front door this past summer from my electricity provider about missed opportunities to have a load control switch installed on my heat pump's outdoor segment as part of their demand response system. One thing I'd like—but haven't yet had the time—to look into is the nature of the broadcast radio communication from the provider to signal these switches. This post is a reminder to myself to investigate this as well as a query to any of you out there with relevant knowledge or tools. What frequency is the power company using for this signaling? Do they have their own spectrum allocation? What legal and/or technical barriers are there to prevent an ordinary person, unaffiliated with the power company, from spoofing the signal and thus disrupting thousands of air conditioning compressors?