Secondary dial tones are often used in call queuing and call forwarding systems. In practice, minimal latency also includes queuing and processing delays. Areas where they have been heavily applied are in inventory, capacity, scheduling, queuing and forecasting. EF traffic is often given strict priority queuing above all other traffic classes. Roundabouts do not stop all entering vehicles, reducing both individual and queuing delays. CFS is an implementation of a well-studied, classic scheduling algorithm called weighted fair queuing. Under normal queuing conditions the cells might experience maximum queuing delays. But there are several types of virtual queuing systems. Some devices feature multiple FIFOs for simultaneously and independently queuing different types of information. IMS TM uses a messaging and queuing paradigm. Measures included the imposition of queuing at ticket gates and turning off some escalators. The priority queuing system was originally controversial. Express Pass is not a virtual queuing service. Or they register with a message queuing service. There are many formulas for various types of queuing theory problems.