Telepati SIP Phone Freeware
Telepati SIP Phone Freeware allows you to make PC-PC phone-phone calls over the Internet. Developed using Research Labs VOIP SIP Phone SDK, this free soft phone brings SIP protocol support for ActiveX. With this phone once you set the gatekeeper proxy with the username and password from your... Now VOIP open source projects have made it easier to implement a customized VOIP Solution eliminating costly PSTN lines. ... Though this implementation might turn out fairly complex, our VOIP Implementation Team at Research-Lab will guide you remotely for the same.
http://www.bandwidthsaver.com/downloads/telepati.zip - 1Mb - Download - Screenshot

VSoft3
The VSoft Phone is a simple to use internet telephone system that can reduce your call costs. It uses the latest technology to let you make calls to friends, family, and business associates anywhere in the world without any chunky telephone equipment. ... VSoft features includes unlimited free VoIP to VoIP call (PC to PC), free video call, low cost VoIP to home/mobile call, send SMS, confrence, SMS to call, VoIP bridge. ... The VSoft Phone utilises a Broadband internet connection to allow a user to make VoIP calls to any phone number worldwide.
http://www.mobif.com.my/Download/VSoft3.3-setup.exe - 4Mb - Download - Screenshot

VOIP Phone Buddy for SKYPE
VOIP Phone Buddy for SKYPE VOIP Phone Buddy for Skype adds automatic telephone dialling to almost any windows application, using SKYPE VOIP telephony, including Microsoft CRM, Microsoft, Access, Microsoft Outlook, Goldmine, ACT, other CRM and Accounts packages etc. ... When the call is selected Skype and Jajah will call you on your own phone and then dial the phone number you selected, using cheap or free phone call! ... Simply move the cursor to a phone number and press the Hot Key to activate "VOIP Phone Buddy for Skype" phone dialer.
http://urlcut.com/voipphonebuddy.exe - 2Mb - Download - Screenshot

3CX VOIP Phone for Windows
Free VOIP / SIP phone. Use your PC as a phone. Works with any SIP / VOIP provider/ phone service. Use instead of the soft phone provided by your VOIP provider which locks you into their VOIP phone service. Easy to use interface includes dial pad and buttons to transfer or forward a call. ... * Search using ENUM * Installation provided as MSI for easy deployment 3CX VOIP Phone for Windows also functions as a client for 3CX Phone System for Windows, a software-based VOIP PBX that completely replaces a traditional proprietary phone system.
http://www.3cx.com/VOIP/3CXPhone.exe - 1Mb - Download - Screenshot

Express Talk VoIP Softphone
Express Talk is software that works like a telephone to let you make calls from your PC. With Express Talk you can call anyone on the internet who has installed Express Talk (or any other SIP voip softphone). Calls are free. You can also call ordinary telephone numbers anywhere in the world if... Features: ~ Lets you make internet phone calls free direct PC to PC, or PC to phone via a VoIP SIP gateway provider. ... Within minutes you will be able to setup the software and start making phone calls.
http://www.audiochannel.net/software/talk.zip - 430Kb - Download - Screenshot

One4000IP
One4000IP, is more than a Netphone that lets you take advantage of free broadband VoIP calling with premium voice quality as well as super low worldwide rates to regular phones without changing your operator. Call from your PC to other PC? s for free or call to regular fixed phones and mobiles... Choose from which one of your registered phone numbers you want to make your call by clicking on one of the buttons: Phone, Mobile or PC. ... Enter the phone number you want to call by clicking on the dial pad (just the way you would have done with a real phone) or by using the key board, click on...
http://www.one4000.com/download/one4000IP_setup.zip - 5Mb - Download - Screenshot

Quorum Call Conference Software
Quorum is software which runs as a phone conference server on any Windows PC. Callers dial into the server to join telephone conferences. Callers can connect to a conference call using either standard or VoIP lines on external telephone numbers or through an office phone system. ... ~ VoIP calls can be made using free VoIP SIP Service Providers saving call costs if they are an issue. ... ~ Easily allocate new conference IDs on the phone. ... ~ Can connect to ordinary phone lines (or analog PBX extensions) directly using telephony devices.
http://www.audiochannel.net/software/quorum.zip - 947Kb - Download - Screenshot

Jajah Phone Buddy
"Jajah phone buddy" adds automatic telephone dialling to almost any windows application, using Jajah VOIP telephony, including Microsoft CRM, Microsoft, Access, Microsoft Outlook, Goldmine, ACT, other CRM and Accounts packages etc.
http://www.jajahphonebuddy.com/download/install.exe - 2Mb - Download - Screenshot

PC-Telephone
Make FREE pc-to-pc, pc-pc and cheap pc-to-phone, pc-phone, pc-to-fax, pc-fax, phone-to-pc, phone-pc, fax-to-pc, fax-pc calls over Internet/VoIP or ISDN/PSTN telephone networks. Use your computer as internet telephone, USB phone, USB handset, ISDN telephone, ISDN fax, answer phone, fax software,... Works with all Firewalls, NAT and LAN routers - nothing to configure.
http://www.pc-telephone.com/download/pc-telephone.exe - 1Mb - Download - Screenshot

FREE PHONE
FREE phone is a SIP based VoIP soft phone, which integrates robust technologies such as SIP stack by NIST (National Institute of Standards and Technology) and Java, JMF from Sun Microsystems. FREE phone is a free downloadable soft phone which enables you to make calls from pc to pc, pc to mobile... FREE phone offers you a free phone number to make free pc to pc calls and receive free incoming calls from any phone. ... Through FREE phone, you can have a live video chat with your FREE phone buddy.
http://www.globe7.com/downloadnow.php?refcode=AX12640 - 16Mb - Download - Screenshot