(a) This subchapter applies only to a county with a population of more than 20,000 or to a group of two or more contiguous counties each with a population of 20,000 or more in which an emergency communication district was created under Chapter 288, Acts of the 69th Legislature, Regular Session, 1985, before January 1, 1988, or to a public agency or group of public agencies that withdraws from participation in a regional plan under Section 771.058(d).
(b) This subchapter does not affect the authority of a public agency to operate under another law authorizing the creation of a district in which 9-1-1 service is provided.