Outsourcing is a widespread phenomenon in business environment. As a rule, companies hand such business functions as accounting, legal support and cargo transportation over to external providers. IT outsourcing has been gaining ground as a efficient concept for small and medium businesses. By outsourcing their IT functions SMB have an opportunity to build and support an efficient IT infrastructure at a minimum expense. Large organizations use outsourcing to focus on their core activities, to optimize maintenance charges and to improve its internal information environment. A Service Level Agreement (SLA) is a guarantee of service quality and reliability.