For example, if your procurement department can agree a UC with their suppliers to deliver hardware within two working days of receiving a purchase order, then your service desk can agree an OLA with the procurement department to receive required hardware within three working days of submitting the request, and can agree a further OLA with hardware support to provide working hardware within four working days of being assigned the call. This then enables the IT support department to agree an RA with the business of providing operational new hardware within a week of the request being logged.
To demonstrate some of the principles of service level management, consider a typical IT support process, where the service desk receives a request for a new PC. The service desk allocates the user a temporary PC, and assigns the request to Hardware Support. Hardware Support raises a Purchase Requisition and the Procurement department then places an order with a supplier. When the PC is received, it is set up by Hardware Support and the request is closed.