Axon Virtual PBx System
Axon is a virtual PBX designed to manage calls within a business or call center environment. Any business, whether small or large, can now implement a scalable PBX solution with an existing PC which connects to phone lines and extensions using VoIP technology. ... Offering all the normal features of a traditional PBX such as allowing internal or external calls and more advanced call queuing for call center applications the software routes all calls within a business. ... ~ Works with hardware type VoIP extensions which just plug into the LAN (eg.
http://www.audiochannel.net/software/pbx.zip - 323Kb - Download - Screenshot

Uplink Skype to Sip Adapter
Uplink connects SIP protocol VoIP calls to the proprietary Skype phone network. It works in both directions. The SIP protocol has become the industry standard for VoIP. Thousands of telephone companies, IP phone manufacturers and virtual IP based PBX systems use this protocol to connect calls. ... The problem is the proprietary IP phone 'Skype' has an almost cult following in the youth market and sometimes the call rates for SkypeOut are discounted. ... Typical Applications: ~ Call centers who want to be able to advertise a Skype number for customers.
http://www.nch.com.au/skypetosip/uplinksetup.exe - 238Kb - Download - Screenshot

Embedded VOIP SIP Developers Kit
Embedded Windows CE VOIP Developers Kit is your embedded telephony solution for developing software/hardware to enable device to device phone calls using SIP/H323 phone right at the electronics level. The design is based on Hybrid Combination of RFC SIP Protocol and Windows RTC and is today... Research Lab further enables you to create production level voip system with following tools Available : A complete multi-lingual speech synthesis workbench using Festival TTS Available: A complete multi-lingual speech recognition workbench using ISIP ASR Available: Speaker Verification (with two...
http://www.ipchip.com/downloads/wincevoipsip01.zip - 2Mb - Download - Screenshot