Tex. Util. Code § 251.009

At least once each calendar year, at intervals not exceeding 15 months, each Class A underground facility operator who conveys, transmits, or distributes by means of its underground facilities service directly to more than one million residential customers within this state shall provide all of its residential customers in this state general information about excavation activities covered by this chapter and the statewide toll-free telephone number established by the corporation.