Correct. I was in the Royal Australian Artillery corps for a number of years, and RATEL procedures (across all corps) drill this into you.

However it is unlikely to occur in practice - the artillery battery will (generally) be on a separate radio net, and the proword will only be applicable if you're in an active fire mission - though it's good to be safe. My wife still gets frustrated with my use of SAY AGAIN.

When you get a good sig on each end, the speed of fire mission comms is a thing of beauty - and once the mission is opened both ends will drop all callsigns.