טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentPolyna Khudyakov
SubjectDesigning a Call Center with an IVR (Interacting Voice
Response)
DepartmentDepartment of Industrial Engineering and Management
Supervisor Full Professor Mandelbaum Avishai


Abstract

A call center is a popular term for a service operation that handles telephone calls of customers. A call center typically consists of agents that handle incoming calls, telephone trunk lines, an Interactive Voice Response (IVR) unit, and a switch that routes calls to agents.

The subject of this thesis is a Markovian model for a call center with an IVR. We calculate operational performance measures, such as the probability for a busy signal and average wait for an agent.  The calculations of these measures are cumbersome and they lack insight.  We thus approximate the measures in an asymptotic regime known as QED (Quality & Efficiency Regime), which is suitable for moderate to large call centers.  The approximations are both insightful and easy to calculate (for up to 1000's of agents).  They yield, as special cases, known approximations for the Erlang-B, Erlang-C and M/M/S/N queue.

Finally, we develop an algorithm for optimal staffing and trunk level.  The algorithm is then used to analyze ways for reducing the operational costs of a call center, to understand the effect of a call center's size on its service level, and to investigate the effect of changes in system parameters on performance - for example, increasing IVR functionality (which would reasonably imply fewer but longer agent calls).