Capture name in IPTC data

Does anyone have a workflow that will place the original camera image number into a IPTC field? I would love to keep track of the original RAW number, even when a processed file has it's name changed down the road.
I could do this in Photoshop, but I'd love to have a failsafe default directly in the Phase software, without the extra Photoshop batch.
Thanks
Dave