如何使用java程序拨打电话

when i connect the mobile phone to computer through usb. So then i want to giv commands usin computer program to phone. As a example Dialing number,busy tone to incoming call like that.... i heard AT command can do this kind of things. is there any possibility to do this job using java command and AT command.. what are the recommended from u. & when i connect the mobile phone to computer thr