Service Level Approximations for a Call Center with Two Customer Types

Abstract

We consider a call center whose customers can be classified into two types depending on their tendency towards waiting in the queue. A customer of type A waits in the queue, if necessary, until he gets served. On the other hand, a type B customer is assumed to be impatient and he does not join the queue and leaves the call center immediately if there is no server available. There are well known formulas for calculating the service levels when a call center serves only one customer type; Erlang delay formula and Erlang loss formula for type A and type B customers, respectively. Hence, there is no such simple analytic result for computing service levels when a call center handles both customer types together. In this paper we suggest and compare several approximation methods to calculate type A and B customer service levels for a call center serving both customer types. Numerical experiments show that one of the methods suggested in this paper approximates closely the actual service level especially when the call center provides high level of service