Which service allows the network to provide better or special services to a set of users and applications at the expense of other users and applications?

QoS encompasses a set of mechanisms - such as traffic marking, queuing, and policing - that allow the network to guarantee bandwidth, reduce latency, and minimize packet loss for designated users or applications while deferring or dropping lower-priority traffic, which is precisely the behavior described in the question.

Dial plans define digit translation and routing logic within a telephony system and have no role in differentiating network service levels.

Route patterns are digit strings configured in CUCM to match dialed numbers and determine call routing destinations, not mechanisms for traffic prioritization.

Dial peers are voice port configuration elements on Cisco IOS routers that define call legs and routing, not tools for providing differential quality or bandwidth guarantees.