Conditional probabilities Given a sequence of words, calculate how often a particular word tends to follow. This equipment is less expensive, less complex and faster and thus more popular than competing more complex technologies that provided QoS mechanisms. Message alerts FAQs: How will I be notified of new messages? The resulting absence of network congestion reduces or eliminates the need for QoS mechanisms. QoS is sometimes used as a quality measure, with many alternative definitions, rather than referring to the ability to reserve resources. Protocols End-to-end quality of service End-to-end quality of service can require a method of coordinating resource allocation between one autonomous system and another.