Zoiper
 
A key-feature for the Zoiper Communicator is that you can choose to use it simultaneously with the Zoiper Service and with your VoIP service provider. Doing so will save you costs and will ensure your continuous communication.

The Zoiper Service is embedded in your Zoiper Communicator and assures FREE advanced Zoiper-to-Zoiper communication.

You can easily configure your SIP and IAX accounts with your existing VoIP provider in your Zoiper Communicator.

X-Lite

CounterPath's X-Lite is the market's leading free SIP based softphone available for download. Combining voice and video calls, Instant Messaging and presence management in an intuitive and familiar interface, X-Lite helps you seamlessly transition from a traditional hard phone environment into the world of Voice over IP.

If you are already a VoIP or Broadband service subscriber (i.e. you receive VoIP service from your local Service Provider or local IP-PBX), X-Lite 3.0 lets you make audio calls to any softphone, mobile or landline number, and make video calls and send IMs to any softphone which supports these functions.

SIP Communicator
 
SIP Communicator is a Java VoIP audio/video Internet phone and instant messenger that supports some of the most popular instant messaging and telephony protocols such as SIP, Jabber, AIM/ICQ, MSN, Yahoo! Messenger, Bonjour, IRC, RSS and counting.

SIP Communicator is completely Open Source / Free Software, and is freely available under the terms of the GNU Lesser General Public License.

WXCommunicator
 
wxCommunicator is a cross platform open source SIP softphone enabling users to make multiple calls, use several accounts, chat and create conferences. It is very configurable and should work with any VoIP provider. It is based on customized sipXtapi client library and wxWidgets 2.8.x GUI library and distributed under GNU GPL version 2 licence.

Voix Phone
 
Voix Phone Is a multiplatform IAX soft phone, its engine derives from Voix Manager, the powerful Asterisk call manager interface, from which it inherits stability and robustness.

Voix Phone has been thought with simplicity in mind, all feature needed by the user, fast and easy usable, with the minimum configurations, just fill the phone login information and play.

We hope that this our contribution could be useful to who requires of a simple but advanced soft phone, Voix Phone is distributed freeware for non commercial use.

Sippax Softphone Dialer
 

Sippax is the leading SIP dialer, work automatically under NAT with new technology UPNP that can handle symetric NAT. Best voice quality with G.723.1 codec and G.729, GSM and G711. Video codec supported are H.263 and H.261.
Sippax support hold function, mute function, mic/spk volume control, audio video configuration wizard, auto login to web billing CDR, call history, address book, balance display, fully
skinable look n feel, available for private label and logo .

Minipax Softphone Dialer
 

Minipax is newest generation of Vidosystem Softphone. Our engineer had successfully recode sip engine to produce more robust, small application, better nat traversal sip softphone.

Minipax NOW support SIP tunneling. SIP tunneling works where clients firewall blocked or on a country where voip is blocked. SIP tunneling also give more security to voip.