Carrot and the stick mentality (minus the carrot) offering rewards but instead increase workload/stress.
Workforce is kept at a quantity that can handle constantly high call volumes, so if/when the calls reduce the opportunity to reduce staff begins. Too many staff means less profit so they will work you to mental exhaustion.
Any mistake will be amplified and praise is at a bare minimum leading to worries about job security and losing your job during quiet periods.
Good luck getting time off, or planning for any event in the future.
Sickness is weakness and you will be made to feel guilty for letting your colleagues down. See earlier point about keeping staff to bare minimum.