35 ILCS 630/20
If any clause, sentence, Section, provision or part of this Article or the application thereof to any person or circumstance, other than the applicability of the Article to messages originating or terminating outside this State, shall be adjudged to be unconstitutional, the remainder of this Article or its application to persons or circumstances other than those to which it is held invalid shall not be affected thereby. In particular, if any provision which exempts or has the effect of exempting some class of persons or some act or privilege of sending or receiving telecommunication from the tax imposed by this Article should be held to constitute or to result in an invalid classification or to be unconstitutional for some other reason, such provision shall be deemed to be severable, with the remainder of this Article, without said provision, being held constitutional.
35 ILCS 630/20