Md. Code, Public Safety § 1–303

(a) (1) This subtitle does not require a public service company to provide any equipment or service other than in accordance with tariffs approved by the Public Service Commission.

(2) The provision of services, the rates, and the extent of liability of a public service company are governed by the tariffs approved by the Public Service Commission.

(b) (1) This subtitle does not require a 9–1–1 service carrier to provide any equipment or service other than the equivalent of the equipment and service required of a telephone company under subsection (a) of this section.

(2) This subtitle does not extend any liability to a 9–1–1 service carrier or seller of prepaid wireless telecommunications service.