Unless there is a private API solution found - our organization is moving forward with placing the IMEI and phone# into our Enterprise Applications as a guarded Application Settings.
With the new camera based barcode recognition of iOS7 - the IMEI can even be scanned from the phone box during initial kitting and deployment rather than entered by hand.
We also considered tracking the identifierForVendor UUID in a database etc. linking to IMEI/Phone# but since it can change and since our historical data is all IMEI based - didn't make sense to add that layer of tracking complexity to a semi-useless identifier that doesn't trace back to a universal meaningful tracking mechanism like Phone/IMEI.