Hi I have read your project with great interest, and would like to lodge my interest. We develop the majority of our work in PHP/MySQL and produce not just websites, but also internet based CRM and management systems, developing Insurance underwriting systems, loan management systems and online medical systems for football clubs. We have developed a chat systems which is integrated to SMS but can be modified and adapted to work in the way you have described. It allows for multiple operators to be chatting at any one time, and allows for users to be assigned to different operators where required. Would be very happy to speak to you about this.