Companies use three general categories of IT support: call-in, block hours and managed services. The first category, also known as time and material services, requires the customer to purchase materials separately and pay for a technician’s services based on a pre-negotiated series of fees, usually at an hourly rate. Block hours, as a modified form of time and material services, allow businesses to pre-purchase information technology support time at a reduced rate. IT support for managed service contracts provides a pre-defined list of support tasks that are available on a continuous basis.