A method for transmitting SMS messages to a subscriber GSM telephone after a call is ended and authenticating the source of the delivered text message with a logo or other graphic not forwardable by mobile phone subscribers is provided. In the present invention, audio advertisements are selected based on a mobile phone subscriber's profile, and accompanying SMS messages or m-coupons are further transmitted to the subscriber only upon their request. A check will be carried out on the eligibility of the subscriber to receive the SMS message they had requested for. This check limits the number of times the subscriber receives a same SMS message. If the subscriber is eligible to receive the message, an authenticating symbol is included in the SMS message before transmission so that retransmission to other users will delete the graphic and render the SMS message invalid for business transactions.