The front-end zMessage is finally installed and works. Both incoming and outgoing SMS can now be handle in GUI without the need to operate in Asterisk CLI.
BTW, I would like to report that Internet Explorer is not 100% compatible with zMessage while Firefox is preferable.
Thanks again for ckleea C-Hing's help and advice so that I can get it done smoothly.
Some one mentioned the use of kannel to send SMS but I doubt if you can use Internet, voice and SMS at the same time. I personally still think it is far more simple to use asterisk on a Linux server.