[Serusers] How to start a VOIP business ?

Sir, I would like to know how can start a successful SIP base VOIP business. I have being going through some documentation of Open server software but could not come to a conclusion. Anybody can suggest me a complete solution for running PC to Phone service Using GPL products, with accounting, authentication and authorization with different rate Plans etc. Here is what I have decided to do. SIP Server (Hardware) 1. Linux RedHat 9.0 2. OpenSer or SIP express router 3. Radius client Accounting /CDR server ( Hardware) 1. Linux Redhat 9.0 2. CDRTool by ag-projects http://www.ag-projects.com/cdrtool.html 3. MySQL 1.Carrirer Subcription to any International whole sale VOIP carrier Please suggest if I have missed anything out. Regards, Concy