Free
OfficeSIP Alerter 1.0
OfficeSIP Alerter is a simple, easy-to-use and free instant sip messenger. It was not designed for prolonged chat, it is handy when you need to send single message. It is good replacement for old-fashioned Alerter Service.
Free
OfficeSIP Server 2.7
Free voice calling between employees over the Internet with OfficeSIP Server