BBM Voice on BBM v7.0 currently works with WiFI enabled, however BBM on the BlackBerry 10 OS will be able to make BBM Calls which include both BBM Voice & BBM Video over your mobile network.
The tricky thing here is how much “data” willit use, will your carriers charge you a special fee to use these added services? Would it just be better to use WiFI? All these are questions to consider, but until we see how much data BBM Calls take up and the quality of the calls, it just might be worth using up your data on.
Source: BBin