Can my employer legally audio record me at work?

i work for an after hours answering service and all our calls and recorded. but if we are not on a call we can unplug our headsets and what we say is not recorded. as of today, my employer installed video cameras with audio recording as well. so now if we have down time and are not on calls, we cannot have private conversations among each other. i understand the video recordings, but since we are already recorded 95% of the time, can they legally record our private conversations? even when they have no regard to the workplace? i feel this is wrong, but maybe im wrong, and if it helps i work in south carolina! thanks