A system and method for handling calls at one or more call centers. In an exemplary method of the invention, it may be determined whether a call should be transferred from the VSS to an agent of a call center based on, for example, agent availability or queue wait times. When it is determined to transfer the call to the agent, it may be determined whether a callback call should be offered to the caller. When it is determined to offer the callback call, the method may include providing one or more time blocks to which the caller can initiate the callback call to receive higher priority routing. Upon calling back into the system within one of the time blocks, the call may receive preferential routing treatment.