Att Tilt Video Can I Make Messenger (yahoo,google Talk) Calls Through My ATT Tilt Phone When Connected To Wifi Or Data-plan ?

Can i make messenger (yahoo,google talk) calls through my ATT Tilt phone when connected to wifi or data-plan ? - att tilt video

When I purchased the iPhone, there's no voice recorder or video recorder, so I plan on ATT Tilt phone, I think he has to buy.
The use ATT Tilt phone, I make Yahoo Messenger or Google Talk or MSN Messenger, Internet telephony, where the Wi-Fi or data plan? Please click on the possibilities that this advice without a data plan was. Your answers are appreciated.