VoIP is becoming more common and practical. Essentially it relies upon transmitting audio data packets with low latency across broadband networks. Most of the VoIP services use the SIP protocol.
Kphone/Pi is a port of KPhone to the Zaurus kphone setup guide
TkcPhone is another Zaurus VoiP program tkcphone homepage
A third application that might be worth trying is Linphone, which also has a gui front end; this may only work for sharp-based (non-OZ) ROMS, however
KPhone SI is a SIP User Agent for Linux. It implements the functionallity of a VoIP Softphone but is not restricted to this. It is licensed under the GNU General Public License. KPhone is written in C++ and uses the Qt-Toolkit.
KPhone SI supports as well Proxy Agents as direct communication between User Agents. The latter may be not possible if firewalls and NATs restrict point-to-point communication. 
The 750,760,860,1000,3x00 have a dual-purpose headphone/microphone socket. When the audio driver is used for audio-in one channel is switched to a microphone input.
It is thus possible to use a universal headset (usually designed for home cordless telephones) with a 2.5mm jack plug with three connection rings, with a 2.5 to 3.5 adaptor, and plug it into the Z to VOIP calls.
The 6000 has a built-in microphone and speaker, so can be used directly, quality suffers due to echo, so a headset is ideal; in this case the 6000 has a 2.5mm jack. I think that the same universal headset should work.
Note that some headsets with 2.5mm jack plugs have four connector rings on the tube, these are designed for mobile phones, with the extra connector being for a push button to answer or dial. These might not be suitable for the Zaurus, but they are useful if you have an Audiovox RTM8000 gsm/grps compact flash modem card (it might also work with an Enfora, but I am not sure)
Original pages, will be removed when the page is mature enough
|VoIP software||There are at least two VoIP apps available|
|VoIP hardware||Headsets and connectivity options|