The binoculars description states that the binoculars include a radio, but the radio pack says to use it in conjunction with binoculars. Do I need a radio pack when spotting? If not what is the purpose of the radio pack? Do the artillery gunners need to a radio to receive info from the spotter?

Descriptions for reference:

Radio pack: A long range radio pack, allowing a spotter to call in long range fire support from afar. Works in conjunction with the binoculars.

Binoculars: binoculars and a portable radio. Useful to coordinate artillery strikes. Using this on a target will mark it, remove the indirect fire penalty from any artillery pieces targeting it. Additionally, any directed fire will use the aiming accuracy and efficiency of the spotter, rather than the artillery operator to determine final accuracy.