Receive sms message through Modem

Question

Please I would like to recieve sms requests from phone number using a modem with my PC. I have the c# code up and running but I need to receive requests from phone's sms messaging system e.g texting, "iTaxi glasgow to london" then send to the number in the modem. So that a reply would be send from the modem's sim immediately. Please help me with advice