(a) An agent of a practitioner commits an offense if the agent communicates by telephone a prescription unless the agent is designated in writing under Section 483.022 as authorized by the practitioner to communicate prescriptions by telephone.
(b) An offense under this section is a Class B misdemeanor unless it is shown on the trial of the defendant that the defendant has previously been convicted of an offense under this chapter, in which event the offense is a Class A misdemeanor.