Texas Code of Criminal Procedure - CRIM P Art. § 18B.101. Order Authorizing Installation and Use of Pen Register, ESN Reader, or Similar Equipment

(a) On presentation of an application under Subchapter B, a judge may order the installation and use of a pen register, ESN reader, or similar equipment by an authorized peace officer commissioned by the department or an authorized peace officer of a designated law enforcement office or agency.

(b) On request of the applicant, the judge shall direct in the order that a communication common carrier or a provider of an electronic communications service provide all information, facilities, and technical assistance necessary to facilitate the installation and use of the device or equipment by the department or designated law enforcement office or agency unobtrusively and with a minimum of interference to the services provided by the carrier or service provider.