roaming tags make data use very expensive (unless you manually initated data and checked things yourself). Telstra was probably quite happy with the arrangement, but I wonder if 3/Voda tried to fix it. If you didn't need data then the 3 coverage combining 3GIS, Telstra & Vodafone was quite extensive and no hidden costs. If your phone could have turned off data when on Telstra it would've been brilliant.