Getting Started with Zfone. What is Zfone?
<<<... For this reason, it is important that you get your VoIP client tested and working before you install Zfone. We don't want to get emails from you complaining that Zfone doesn't work, when you haven't first established that your VoIP client works in your local network environment. Windows users must not interrupt the installation process! We warned you about this earlier on the Getting Started with Zfone page and then we warned you again on the download page for the Windows version, but it bears repeating here: Windows users should not interrupt the installation process, despite multiple warnings stating that the ZRTP Miniport driver is not Windows Logo certified. If you interrupt the installation, there will be various harmful effects, including crashing the system. It's dangerous to interrupt the installation of any device driver on Windows, including this one.
If Zfone for Windows crashes, you can always use the Windows Recovery Console to roll back all changes caused by installing Zfone. For additional information see: http://www.microsoft.com/windowsxp/using/helpandsupport/learnmore/systemrestore.mspx and http://www.microsoft.com/windowsxp/using/helpandsupport/getstarted/ballew_03may19.mspx.
Note that Zfone runs on the 32-bit version of Windows XP, but not the 64-bit version, and also not on Vista. We do plan to support 64-bit Windows XP Pro in a future release. Known "Issues" Most of the trouble we have with this implementation of Zfone stems from the complexity of detecting the VoIP client's SIP and RTP packets on the fly, figuring out what UDP port numbers they use, and triggering ZRTP protocol whenever these packets are detected. That whole class of problems would disappear if the ZRTP protocol were integrated inside a VoIP client. The packet detection problems only arise because we implement the ZRTP protocol in this particular product outside the VoIP client as a "bump in the cord"... more>>>