When calls reach an unacceptable level in the queue, there are any number of manual interventions which can be made. Many call centres adopt the approach of thinning out the queue by creating short calls.

This is done by asking the caller if they would accept a later call back.  This is normally undertaken, assertively, by stating there are no appropriate available agents.

Software is also available to make this happen more dynamically without human intervention.  The software allows the caller to leave contact details for a later call back. The software then holds-on in place of the caller - details are then passed to the next available agent to undertake the call back.

These methods are designed to reduce cost, improve service, handle peaks in a smoother fashion and remove agent stress and inaccuarcy.