I smiled a bit here, watching the attempts to fit channel names to content. realistically, it's simply a nice, neat term, perhaps borrowed from other systems for day to day activity. My hire radios have R1, S1, S2 and S3 in the display. One of my clients who do security have R1, tac1 and Tac2. The reason is that I watch NCIS, and I noticed one day they grab radios and somebody shouted TAC1. Here, we use talk-through quite often to describe repeater use, but a few people use talk-around because it's often a term used by the manufacturers in their documents. It's a name they use, and I suspect few people know or care within that organisation what it stands for - it just 'is'. In the UK, our encrypted country wide emergency system is called Airwave, but uses TETRA protocols. Most Police Officers just call them radios. Most won't have a clue they are TETRA, and a few know it's Airwave - to most, if you ask them, they just turn a knob till the normal channel appears in the display and the press a button to talk.