miniSipServer (100 clients) - professional IP PBX for windows
mini SIP Server is a SIP Server / VOIP server for Windows system, such as Windows 2000/XP/2003/2008/Vista, and Windows7! mini SIP Server is based on the SIP standard which is an open standard. There are so many SIP phones (software or hardware), you can choose anyone you like without vendor lock in. It is very easy to setup and manage your own VOIP system. In fact, you can use MSS to deploy a basic VOIP network in 1 hour!