Submitted papers:

  1. Optimal contact center staffing and scheduling with machine learning (with Siqiao Li and Qingchen Wang).
  2. Waiting-time distributions in call blending models (with René Bekker, Petra Vis and Bartlomiej Zaber).
  3. Cost-optimal call center forecasting and staffing (with Sihan Ding).
  4. Outsourcing and reservation; tools to manage blended sales and services operations in call centers (with Benjamin Legros and Oualid Jouini).

Refereed papers:

  1. Blended call center with idling times during the call service (with Benjamin Legros and Oualid Jouini).
    IISE Transactions 50(4):279-297, 2018.
  2. A uniformization approach for the dynamic control of multi-server queueing systems with abandonments (with Benjamin Legros and Oualid Jouini).
    Operations Research 66(1):200-209, 2018.
  3. Flexible staffing for call centers with non-stationary arrival rates (with Alex Roubos and Sandjai Bhulai).
    In Markov Decision Processes in Practice (Richard Boucherie and Nico van Dijk, eds), Springer, 2017.
  4. Optimal scheduling in call centers with a callback option (with Benjamin Legros and Oualid Jouini).
    Performance Evaluation 95:1–40, 2016.
  5. On the estimation of the true demand in call centers with redials and reconnects (with Sihan Ding and Rob van der Mei).
    European Journal of Operational Research 246(1):250-262, 2015.
  6. Optimization of overflow policies in call centers (with Bo Nielsen and Thomas Nielsen).
    Probability in the Engineering and Informational Sciences 29(3):461-471, 2015.
  7. Adaptive threshold policies for multi-channel call centers (with Benjamin Legros and Oualid Jouini).
    IIE Transactions 47(4):414-430, 2015.
  8. Dynamic call center routing policies using call waiting and agent idle times (with Wyean Chan and Pierre L'Ecuyer).
    Manufacturing & Service Operations Management 16(4):544–560, 2014.
  9. Performance indicators for call centers with impatience (with Oualid Jouini and Alex Roubos).
    IIE Transactions 45(3):341-354, 2013.
  10. First in line waiting times as a tool for analyzing queueing systems (with Bo Nielsen and Thomas Nielsen).
    Operations Research 60(5):1258-1266, 2012.
  11. Service level variability of inbound call centers (with Alex Roubos and Raik Stolletz).
    Manufacturing & Service Operations Management 14(3):402-413, 2012.
  12. Staffing a call center with uncertain non-stationary arrival rate and flexibility (with Shuangqing Liao, Christian van Delft and Oualid Jouini).
    OR Spectrum 34(3):691-721, 2012.
  13. A note on profit maximization and monotonicity for inbound call centers (with Auke Pot).
    Operations Research 59(5):1304-1308, 2011.
  14. Queues with waiting time dependent service (with René Bekker, Thomas Nielsen and Bo Nielsen).
    Queueing Systems 68(1):61-78, 2011.
  15. Online scheduling policies for multiclass call centers with impatient customers (with Oualid Jouini, Auke Pot, and Yves Dallery).
    European Journal of Operational Research 207:258-268, 2010.
  16. A simple staffing method for multi-skill call centers (with Auke Pot and Sandjai Bhulai).
    Manufacturing & Service Operations Management 10:421-428, 2008.
  17. Simple methods for shift scheduling in multi-skill call centers (with Sandjai Bhulai and Auke Pot).
    Manufacturing & Service Operations Management 10:411-420, 2008.
  18. Approximating multi-skill blocking systems by hyperexponential decomposition (with Geert Jan Franx and Auke Pot).
    Performance Evaluation 63:799-824, 2006.
  19. Scaling and comparison of fluid limits of queues applied to call centers with time-varying parameters (with Tania Jiménez).
    OR Spectrum 26:413-422, 2004.
  20. A formula for tail probabilities of Cox distributions.
    Journal of Applied Probability 41:935-938, 2004.
  21. Telephone call centers: Tutorial, review, and research prospects (with Noah Gans and Avishai Mandelbaum).
    Manufacturing and Service Operations Management 5:79-141, 2003.
  22. Optimal shift scheduling with a global service level constraint (with Erik van der Sluis).
    IIE Transactions 35:1049-1055, 2003.
  23. A queueing model for call blending in call centers (with Sandjai Bhulai).
    IEEE Transactions on Automatic Control 48:1434-1438, 2003.
  24. Queueing models of call centers: An introduction (with Avishai Mandelbaum).
    Annals of Operations Research 113:41-59, 2002.
  25. Managing uncertainty in call centres using Poisson mixtures (with Geurt Jongbloed).
    Applied Stochastic Models in Business and Industry 17:307-318, 2001.
  26. On optimal call admission control in a resource-sharing system (with Eitan Altman and Tania Jiménez).
    IEEE Transactions on Communications 49:1659-1668, 2001.

Other scientific papers:

  1. A simple solution for optimizing weekly agent scheduling in a multi-skill multi-channel contact center (with Siqiao Li and Oualid Jouini). Proceedings of the 2019 Winter Simulation Conference.
  2. A method for estimation of redial and reconnect probabilities in call centers (with Sihan Ding and Rob van der Mei). Proceedings of the 2013 Winter Simulation Conference.
  3. Call center capacity allocation with random workload (with Shuangqing Liao, Christian van Delft, Yves Dallery, and Oualid Jouini).
    Proceedings of the 2009 International Conference on Computers & Industrial Engineering, July 6-8, Troyes, France.
  4. Approximate dynamic programming in multi-skill call centers (with Auke Pot).
    Proceedings of the 2005 Winter Simulation Conference.
  5. Performance analysis and optimization in customer contact centers.
    Proceedings of QEST 04, Enschede, pages 2-5, 2004.
  6. Routing heuristics for multi-skill call centers (with Auke Pot and Jérôme Talim).
    Proceedings of the 2003 Winter Simulation Conference, New Orleans, pages 1813-1816, 2003.
  7. The mathematics of call centers.
    ``Research highlight'', Biennual report Stieltjes Institute, pages 31-35, 2000/2001.
  8. Exponential approximation of multi-skill call centers architecture (with Jérôme Talim).
    In Proceedings of QNETs 2000, Ilkley (UK), pages 23/1-10, 2000.

Publications in the professional literature:

  1. Posts at WFManagement blog.
  2. Errors in Erlang97 Excel add-in module/Fouten in Erlang97 Excel add-in module (with Karin van Eeden and Edwin van der Hilst).
    Telecommerce Nieuwsbrief week 4, 23 January 2013.
  3. WFM - Kosten, winst, SL en klanttevredenheid (with Annemiek van Moorst).
    Call Center Magazine 11(6):14-16, 2005.
  4. WFM en de kwaliteit van data (with Annemiek van Moorst).
    Call Center Magazine 11(4):14-16, 2005.
  5. Schaalvoordeel en skills bijten elkaar (with Annemiek van Moorst).
    Call Center Magazine 11(2):14-15, 2005.
  6. WFM: goede voorspelling noodzakelijk maar niet voldoende (with Annemiek van Moorst).
    Call Center Magazine 11(1):16-18, 2005.

Popular-scientific articles:

  1. Over wiskundig modelleren en call centers.
    Nieuwe Wiskrant 20(3):8-12, 2001.



  1. Call center optimization.
    MG books, Amsterdam, 2013.
  2. Optimization of business processes.
    Lecture notes.

Editorial work:

  1. Special issue on call center management.
    Management Science 54(2), 2008.

Press articles:

  1. Zwaarder geschut op planning nodig.
    Telecommerce Magazine 06, 2011.