SipDroid provides a SIP/VoIP-Client to your Freerunner with Android by adding native SIP/VoIP to Android's dialer/contacts. You are able to make and receive calls over Wifi, 3G, and EDGE with good voice quality and low delay. SipDroid is capable to receive a Video-SIP/VoIP-Call. Sending Video is not possible with your Freerunner because a Camera is missing.
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 sipdroid.org for configuration tutorials.