Employer installing surveillance microphones and cameras in the business

My boss is going for umrah and I have been tasked with managing the business in his absence. While I was away over the weekend he installed a microphone listening device that he connected to the camera system. I understand that cameras are necessary and assist us in the event that customers have queries. I am unhappy with the listening device and feel that it is an invasion of privacy. What happens if I recieve a personal and private call from my wife? Please let me know if it is Islamically correct to use such systems to spy on staff and if I am justified in feeling unhappt about it.