Hi,
you can use maybe the indicator sdcch requests for MOC wich tells how many percent of calls were MOC. And use that percentage for calculation of:
Revenue=60*(sdcch_req_MOC% * E)* tariff.
sdcch_req_MOC%=sdcch_req_MOC/(sdcch_allrequests-sdcch_imsi_detach-sdcch_LU-sdcch_sms-sdcch_mobile_terminated-sdcch_other). It gives you aproximate value of originated calls.