C4C: Object Identifier Mapping WebService - Employee type codes
The C4C object identifier webservice (CommunicationServicesManagementQueryObjectIdentifierMappingIn/Query Object Identifier Mappings) only works if you supply the correct Remote and Local ID type code. Thankfully, the documentation (linked above) provides a list of type codes for commonly used objects, however, the employee business object is missing.
To make it short, the type codes for employee are: