Service level agreements are also defined at different levels: service level agreements can contain many service performance metrics with service level targets. A common case in IT services management is a call center or service desk. Among the measures agreed in these cases are: like most start-up deadlines, parties to a service agreement may disagree on the terms or on whether or not the other party has fulfilled its share of the agreement. In this case, the disgruntled party can get an appeal. If this is the case, the parties may have to resort to arbitration or legal action, depending on the terms of the contract. If the arbitration procedure is not specified in the contract, the disgruntled party will normally apply to the judicial and intro-duite system. When service contracts cover products, the contract may include repairs, exchanges of funds, product replacement, product diagnosis, parts or software updates, sending a service agent to perform repairs, refunds and/or returns. Since the late 1980s, SLAs have been used by fixed-line operators. Today, ALS is so widespread that large organizations have many different ALSs within the company itself. Two different units in an organization script an ALS, one unit being the customer and another the service provider. This helps maintain the same quality of service between different units of the organization and in several sites within the organization. This internal ALS script also compares the quality of service between an internal service and an external service provider.
 As applications are moved from dedicated hardware to the cloud, they must reach the same level of service, or even more sophisticated than conventional installations. SLAs for cloud services focus on data center features and more recently include network features (see Carrier`s Cloud) to support end-to-end SLAs.  A Service Level Contract (SLA) is an obligation between a service provider and a customer.