Technically its not invasion of privacy because it is their phones in their business. Myself coming from upper corporate management I am used to the phones being monitored and my life at work being under the microscope so it is no big deal to me.
But I think they need to give the employees a heads up and let them know that the calls are monitored. And they need to have the disclaimer to let the customer know that the call might be monitored.
Do I think they are breaking the law? It is up to the statutes that your state has set up for this certain issue.
Billy