You have to pay for the sms you send. If you are trying out on your own, you need a mobile phone with some hardware. You cannot send for free this way. Your balance in the mobile is charged for every message you send. So if your provider gives free sms to send, then you can do so. One of my friends has set up such a system where in he connects his mobile to some hardware which in turn is connected to PC. So, he can send and recieve messages through PC. He uses it for sending bulk messages. If you are interested in doing so, I can ask him more information about it and how to go about setting up one. Let me know.
Update: I asked him about this, you basically need to connect your Phone to PC and use a software to take control of the mobile to send messages. There are many software to send messages through PC, like
this one. Is this a solution to your needs? I think you want it some other way. He also told about SMS gateway to send through web. May be you can browse the web to get more info on how to go about it.
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