As posted by Letscode, you will have to use the SMPP server of the celular service provider. Depending on the country and the provider, it may be from easy to imposible to have them give you access to it. They may require a VPN connection to the computer making it happen. If you are going to use SMPP, you will need WinSock to create the connection and you will have to visit
http://www.smsforum.net to learn SMPP. There yet is another way to do it. Read my next reply.