2 FIA radios (R-148E and RF-10) have different encryption keys such that they aren't interoperable. The R-148E uses the key 'candleSauce' (consistent with FIA configuration in Conflict) whilst the RF-10 uses 'ViktorTroskaLives' (not in any of the configs afaik).

Additionally, the 2 FIA radios do not have their default channels set to FIA platoon frequency (52 MHz) which is what the radio interface shows as platoon for FIA. Instead, the former is set to 42 MHz (Soviet platoon) while the latter uses 48 MHz (US platoon) by default. Of course because of the different encryption keys there's no reception of enemy transmissions (nor friendly from the other transmitter type), but the channel default settings are odd.

N.B. these issues predate 1.7 patch by a while, but now with FIA being playable, they're more relevant now.