Using the free Fring application, you can easily use WiFi to connect to Freespeech. The settings are easy enough:
* Click on "more" on the Fring main page
* Click on "Add-ons"
* Select SIP
* Choose "Other" from the list (at the end)
* Input your user ID (0769999999)
* Input your Freespeech password
* Provide "freespeech.ie" for proxy
* Click on the login button

It should now return to the list of add-ons with a tick beside SIP. You can verify that it works by clicking on the Dialer button, which will display a "SIP" button as well as the usual "Cellular" button.