SMS Auto-Response System based on Keyword

I want a software that will use a sim modem from a local network operator and will have its own inbox and outbox. But mainly it should be able to send out auto replies based on specific sett keywords. When an SMS is received from a number in the address book with a set keyword, the system should be able to send back an automatic reply to that particular number. An example. I want to send out the score of a football game for a particular team called "United". I recieve an SMS from a number which is already in my addressbook, the text reads the word "UNITED"... the system should be able to send an auto reponse immediately of the score which is being updated in the system. The reply should read something like "United 2- FC 0 (43 minutes)" this part is set and updated in the system