Generally, both state and federal law prohibit eavesdropping on confidential communications. Such eavesdropping can occur in the workplace through the monitoring of telephone calls, or through the use of tape recorders to record confidential conversations. However, an employee may consent to the monitoring of his or her communications.
Many employers will require as a condition of employment, a signed statement by an employee acknowledging that the telephone calls made during the course of business are not considered confidential communications. The employee basically consents to the monitoring by the employer. Under these circumstances, such communications are not considered "confidential," because there is not a "reasonable expectation" of privacy.
Unlimited monitoring is unlawful under the Electronic Communications Privacy Act of 1986 (ECPA), so courts will explore the reasons behind employee monitoring, and limit the scope of monitoring if necessary. The courts have ruled that employers can lawfully intercept "business" communications, but have limited rights to monitor "personal communications".