You should be fine just adding it to the conditions on your Left Outer Join:
From CTE cdr Inner Join
dbo.Carrier c on c.CarrierId = cdr.CarrierId Inner Join
dbo.RouteRanges rr With(NoLock) On cdr.RouteRangeId = rr.RouteRangeId Inner Join
dbo.Route r With(NoLock) On rr.RouteId = r.RouteId Inner Join
dbo.Switch s With(NoLock) On r.SwitchId = s.SwitchId Inner Join
dbo.Destination d With(NoLock) On cdr.DestinationId = d.DestinationId Inner Join
dbo.DestinationBand db on db.DestinationBandId = d.DestinationBandId Inner Join
dbo.RateBatch b on b.BatchId = cdr.BatchId Inner Join
dbo.RateDeployBatch rdb on b.DeployBatchid = rdb.DeployBatchId Left Outer Join
dbo.ExportRoamingDetails e on e.FileDate = rdb.RoamingDate And e.CarrierId = cdr.CarrierId And e.RAP = 0 Left Outer Join
dbo.ExportRoamingExchangeRate e2 On rdb.RoamingDate = e2.FileDate Left Outer Join
dbo.ExchangeRate er on e2.ExchangeRateId = er.ExchangeRateId
and er.TargetCurrencyId = @CurrencyId
and er.CarrierId Is Null
and er.Deleted = 0
Left Outer Join
dbo.ExportFile ef on ef.ExportFileId = e.ExportFileId Inner Join
dbo.Prefix p With(NoLock) On cdr.PrefixId = p.PrefixId Inner Join
dbo.AccessTypeCode atc With(NoLock) On cdr.AccessTypeCodeId = atc.AccessTypeCodeId Inner Join
dbo.CallClassCode ccc With(NoLock) On cdr.CallClassCodeId = ccc.CallClassCodeId Inner Join
dbo.PartialCallCode pcc With(NoLock) On cdr.PartialCallCodeId = pcc.PartialCallCodeId Inner Join
dbo.QualityOfServiceCode qofc With(NoLock) On cdr.QualityOfServiceCodeId = qofc.QualityOfServiceCodeId Inner Join
dbo.TrafficTypeCode ttc With(NoLock) On cdr.TrafficTypeCodeId = ttc.TrafficTypeCodeId Inner Join
dbo.CDRFile f With(NoLock) On cdr.FileId = f.FileId Inner Join
#tempba ba on cdr.CarrierId = ba.CarrierId and cdr.DestinationId = ba.DestinationId