A traditional FM walkie-talkie, yes, passive, but a P25/DMR handheld radio, especially operating in trunked mode, not necessarily. One notorious example of this

A traditional FM walkie-talkie, yes, passive, but a P25/DMR handheld radio, especially operating in trunked mode, not necessarily. One notorious example of this is P25's use of packet retransmission requests: https://www.mattblaze.org/papers/p25sec.pdf https://www.mattblaze.org/papers/p25sec.pdf A lot of worksite-oriented handheld radios these days are not just oldschool FM and use digital protocols to efficiently manage bandwidth, which can involve transmitting when not actually sending voice data. I haven't seen any confirmation of whether the affected devices were digital or not, but if they were buying COTS radio equipment there's a decent chance that they were.