Free WiFi Calls On iPhone?

[wrkactjob]

I know that over a mutual wifi connection two iphones can facetime chat for free, but what if you just want to chat and not see each other?...is that possible?

 

[dickdaney]

Talkatone can use you google voice account and number to make wifi calls to land lines.

 

[iKennett]

the release notes make mention to "voice chat in iOS 5" so not sure what this means.