(a) As used in this Section, “telemarketing” means a plan, program, or campaign which is conducted to induce the purchase of goods or services by use of one or more telephones and which involves calls to or from more than one consumer.
     (b) A person or entity that, by means of a telemarketing plan, program, or campaign, offers free goods or services to an Illinois consumer on a trial basis and assesses a periodic fee or charge for the goods or services after the end of the free trial period must send to the consumer who accepts the free goods or services an invoice that the consumer may use to pay the periodic fee or charge or indicate that the consumer no longer wishes to receive the goods or services after the end of the free trial period. The invoice must contain an address and telephone number the consumer may use to cancel the goods or services if the consumer no longer wishes to receive the free goods or services after the end of the free trial period.
     (c) Violation of this Section constitutes an unlawful practice within the meaning of this Act.