For example, while an end customer as a whole may have financial bargaining power with a provider, some sites are unlikely to have a consistent SLA for some sites, with each service having its own back-to-back SLA with the carrier. Although it is assumed that the service level agreement comes from network service providers, the use of these agreements has penetrated the world of information technology and now extends beyond and to the provision of outsourced services. The exact metrics for a service level differ from vendor to vendor. In addition, they differ for individual services purchased by the end customer. Among the metrics that can be indicated by slAs are: Many SLAs comply with the specifications of the Information Technology Infrastructure Library when applied to IT services.