(a) The commercial electronic text message is transmitted at the direction of a person offering cellular telephone or pager service to the person's existing subscriber at no cost to the subscriber unless the subscriber has indicated that he or she is not willing to receive further commercial text messages from the person; or
(b) The unsolicited commercial electronic text message is transmitted by a person to a subscriber and the subscriber has clearly and affirmatively consented in advance to receive these text messages.
(2) No person offering cellular or pager service may be held liable for serving merely as an intermediary between the sender and the recipient of a commercial electronic text message sent in violation of this chapter unless the person is assisting in the transmission of the commercial electronic text message.