3 G DATA CARD

I had purchased one 3 G data card of BSNL from Patna using a 2 G Sim. Then after two days I shifted to Mumbai. I was told by the dealer that it will work in roaming anywhere in India including Mumbai & Delhi (MTNL operators). When I reached Mumbai and tried access internet through that DATA CARD, it was not possible. I can access on the mobile but the roaming charges are deducted on that but, on DATA CARD I am not able to to do so. It always shows error no. 619 where as network of MTNL is always available. What shoul I do to access internet through the DATA CARD. please help.