Hi tchart, thanks for the info but I had already put this confirmation process in motion by firing off emails to the manufacturers (Mitac computers in Taiwan) about the build status of the Tablet I am using.
So just to close down this thread, the manufacturer has fianlly replied and confirmed to me that the 3G module they use does NOT make voice calls it can only be used for Data calls.
So if anyone else are having any problems in this area then confirm first the unit will actually make a voice call, I have another Industrial Tablet which is the rugged version of the Google Nexus 7 which has the same condition, Data enabled but Voice Not enabled.
Looks like the Data module they are all using is cheaper than a combined Voice & Data module.
So thank you all again for your help.