Ours were Nextel, which I think became "Boost Mobile". Prior to the Nextel service (which did use the cell network), we used a radio based service, with brick sized walkie talkies. The service had repeaters so we could reach anyone over a 200 mile range, but the annoying thing was we shared the service with many others. They dealt with this by having customer specific subcarriers, so the radio would only unsquelch for our conversations, but there would be collisions that were undetectible by the originator. The Nextel system was much more reliable.

We used these heavily in the years before cell phones, so it may have been more habit to want ppt and get rid of the brick. We don't use ptt any more, just normal cell calls. I don't know of any contractors that still do use ppt. I'm guessing that's why they are marketing it to the public now.