I think, i didn't provide much information in the question. We have a website where user subscribe with their Mobile No. and Indian Railway PNR. We send them their PNR status updates via bulk SMS package which we have bought from some third party service. Now each SMS cost us money, but we didn't figure out how we can make money by sending SMS to thouse users. (i.e. putting advertisement in SMS, but didn't find any Ad network provide such feature for SMS).