Need to setup VOIP SOHO from Singaporep

Can anyone guide me to setup low cost voip solution through BroadBand Internet.Actually i would like to limit access of about 200 members.

Since I want to set this from my home, i need info about what Hardware and software I need.

I would like to provide 5 Digit Pin number to my registered users, for each user and they can call that number from their registered Phone to hear a dial tone and proceed to Dial the long distance number.

Email Me:vkram@singnet.com.sg / mikkyvikky@hotmail.com

Thanks & Regards
Vikram