Call Center World 2015 takes place in Berlin, Germany, during February 24-26. I will meet some customers and visit the show for one day. If anyone wants to meet at the event or for some drinks in the evening at a nice place in Berlin, contact me.
Kamailio has a lot of features that can be useful in such deployments, including a module for music on hold queuing. Features such as load balancing or least cost routing can help scaling as well as saving costs on outbound calls.
Be sure you register for Kamailio World Conference, during May 27-29, 2015 - it is the place to meet the people behind the project and learn how to get the best out of Kamailio.