SipDroid
From Openmoko
Overview
SipDroid provides a SIP/VoIP-Client to your Freerunner with Android by adding native SIP/VoIP support to Android's dialer and contacts. You are able to make and receive SIP/VoIP-calls over Wifi, 3G, and EDGE with good voice quality and low delay. SipDroid is capable to receive a Video-SIP/VoIP-Call on you freerunner. Of course sending Video is not possible because your Freerunner does not have a camera.
Installation
Start Browser on you installed Android with the URL: http://code.google.com/p/sipdroid/downloads/list , click on apk-File for download. After download execute file with the context menu in the download list.
See [http://www.sipdroid.org] for configuration tutorials.