There are two key prerequisites before you can partake in the free mobile VoIP calls offered by WiFiMobile. First, you must have a Nokia S60 handset. Second, said handset must have integrated WiFi. After all, how do you expect to do the wireless VoIP dance if you can’t wirelessly access the internet on your cell phone? I’m sure that mobile operators like T-Mobile and Rogers Wireless will not be all that happy to hear about services like these, because it allows the consumer to make free calls to one another over a WiFi network, minimizing the amount of charged airtime.

The basic WiFiMobile service is absolutely free and lets you do the basic voice call thing with other VoIP users, but when you step up to the premium service, you gain the ability to make calls to ordinary landlines or mobile phones. While exact prices were not outlined in the press release, they do say that these premium calls come “at heavily discounted costs.”

When you find yourself outside of a WiFi hotspot, you can alternatively use your 3G high-speed data plan to access the WiFiMobile service, though that’ll start to eat up your megabytes (unless you have unlimited data, of course). More details can be found at WiFiMobile.com.