It would be a lot easier to assist you if you could provide a packaged workbook with your issue. I try to reference Shawn's handy guide as much as possible:
From the sound of your description, you might be able to create a conditional measure as a calculated field by setting up an IF statement. If you are always selecting a single employee, you could potentially use a parameter to dictate what goes into the calculated field, and then you can have an unfiltered version of your LiveCall measure in the same view.
Another option might be to utilize a duplicate data source. A filter will only apply to one data source, so you could pull the LiveCall measure from the filtered source in conjunction with the LiveCall measure from the unfiltered copy.
Hopefully that's helpful. If you need further assistance, please provide a packaged workbook.