Identity management (IdM) in essence refers to the management or administration of individual identities within a system, such as a company or network.
Within the corporate world, ID management refers more specifically to providing IT managers with a centralised administrative system (Identity Management System – IdMS) where company users and permission restrictions to applications such as ERP, CRM, e-mail client etc etc can be grouped together and managed collectively. The principle objective behind IdM is to improve security and protection for sensitive company data and systems, whilst simultaneously improving productivity as well as reducing costs, downtime and repetitive time consuming tasks. 
Example Set Up
What makes Identity Management Systems such as Univention Corporate Server (UCS) so useful is that they can be integrated into a whole host of systems including for example corporate phone systems like pascom’s mobydick VoIP Communications Solution as illustrated by the following video.