Yes, consent of all parties to the recording is required, BUT the employer can make it a condition of employement that you must consent. If they tell their employees that conversations are work will be recorded and you continue to work there after notice of that, your choice to continue employment when you are aware of the recording policy will  be taken as your consent to be recorded. If they accidently capture a non-employee on the recording (a guest or visitor) who was unaware of the recording policy and so could not be taken to have consented, then they would be violating the law.