FRAMINGHAM, MASS. -- Recent data from International Data Corp., a division of International Data Group, indicate that revenue in the call center out-sourcing market is heading into a period of growth and transition. IDC foresees an increase of 15-25% annually for the next two to three years in the call center out-sourcing market. Many companies are out-sourcing their call centers and relying on them as a means of connecting with their customers. These companies are demanding that call centers provide more than just teleservices. ``Over time, call centers will transition into customer interaction centers,'' said IDC's Katie Menzigian. ``They will increasingly adopt advanced computer telephony, e-mail, Internet and voice-recognition capabilities.''