(a) It shall not be unlawful under this chapter for an operator of a switchboard, or an officer, employee or agent of any communication common carrier whose facilities are used in the transmission of a wire communication, to intercept, disclose or use that communication in the normal course of his employment while engaged in any activity which is a necessary incident to the rendition of his service or to the protection of the rights or property of the carrier of such communication, provided such communication common carriers shall not utilize service observing or random monitoring except for mechanical or service quality control checks.(b) It shall not be unlawful under this chapter for an officer, employee or agent of any communications common carrier to provide information or facilities to an investigative officer who, pursuant to this chapter, is authorized to intercept a wire communication.