Queuing with Impatient Customers and Ordered Service

Two types of customer behavior are considered: (1) if a customer is acquired for service before he has waited a time τ₀, he remains in the queue until served irrespective of whether or not his total waiting time exceeds τ₀. Only those customers who wait for a time τ₀ without being acquired for service become “lost” customers, and (2) a customer whose total waiting time is τ₀ becomes a lost customer irrespective of whether he is acquired for service or not.