(b) In this section, "authorized peace officer," "communications common carrier," "pen register," and "trap and trace device" have the meanings assigned by Article 18.21, Code of Criminal Procedure.

(c) [amended 9/1/97] It is an affirmative defense to prosecution under Subsection (a) that the actor is:

(1) an officer, employee, or agent of a communications common carrier and the actor installs or uses a device or equipment to record a number dialed from or to a telephone instrument in the normal course of business of the carrier for purposes of:

(A) protecting property or services provided by the carrier; or

(B) assisting another who the actor reasonably believes to be a peace officer authorized to install or use a pen register or trap and trace device under Article 18.21, Code of Criminal Procedure;

(2) an officer, employee, or agent of a lawful enterprise and the actor installs or uses a device or equipment while engaged in an activity that:

(A) is a necessary incident to the rendition of service or to the protection of property of or services provided by the enterprise; and

(B) is not made for the purpose of gathering information for a law enforcement agency or private investigative agency, other than information related to the theft of communication or information services provided by the enterprise; or

(3) a person authorized to install or use a pen register or trap and trace device under Article 18.21, Code of Criminal Procedure.

(d) An offense under this section is a state jail felony.

(a) Except as authorized by a court order obtained under Article 18.21, Code of Criminal Procedure, or in an emergency under the circumstances described and permitted under that article, a person commits an offense if he knowingly installs or utilizes a pen register or trap and trace device to record telephone numbers dialed from or to a telephone instrument.

(c) It is an exception to the application of Subsection (a) that an officer, employee, or agent of a communications common carrier installs or utilizes a device or equipment to record the numbers dialed from or to a telephone instrument in the normal course of business of the carrier, for the protection of property or services provided by the carrier, or assists an authorized peace officer in executing an order issued under Article 18.21, Code of Criminal Procedure.

(d) It is an exception to the application of Subsection (a) that the installation or utilization of a pen register or trap and trace device was made by an officer, agent, or employee of a lawful enterprise while engaged in an activity that is a necessary incident to the rendition of service or to the protection of property of or services provided by the enterprise, and was not made for the purpose of gathering information for a law enforcement agency or private investigative agency, other than information related to the theft of communication or information services provided by the enterprise.