Impersonation: In E-Comm site, this is a important flow where essentially a telesales rep or admin places an order for a regular user, the admin is essentially impersonating the user and WebSphere commerce provides out of box flows to use this behavior.
If your using SalesCenter or have your own Telesales tool customization to work with websphere commerce, you need to add a flag in wc-server.xml after V7 migration.
Until V7 by default impersonation feature was available and would work but essentially there is a flag introduce that needs to be added in wc-server.xml in the instance section during V7 migration if you are using impersonation.
API Background on Impersonation in WCS
getCallerId() --> returns the admin user Id when doing impersonation.
getUserid() --> Returns the userId of the user in the current session.
Important commands for Impersonation for setting user and admin for various commerce operations.
RunAsUserSetInSessionCmd and RestoreOriginalUserSetInSessionCmd