I was Radio Teletype operator . . a very skate MOS
It varied widely. I was an 05B MOS (interspeed radio operator).
In Vietnam at least in my Air Mobile infantry unit, that MOS gave you a 25lb radio (infamous prick25) to hump in the jungle along with all your regular gear. They supposedly had a 15 second or so life expectancy in a firefight because the VC and NVA knew to take out the radios to keep the artillery, gunships and fighter bombers away.
I lasted 7 months thru TET 68 and a good 20+ Air Assaults before their statistics caught up with me, but was better than 15 seconds.