First, be sure which minute bundle you have been activated in Banglalink. If you took the Banglalink to Banglalink minute bundle it means you are using on-net minute. To check the remaining on-net minute balance in Banglalink, you have to dial *222*2#.
If you have brought the Banglalink to all other sim minute bundles it means you are using the off-net minute. To check the of-net Banglalink remaining minute balance dial *222*9#.