Call queue is a service which enables the recipient of the incoming calls to hold 2 or more simultaneous phone calls in a queue. Some companies have large volumes of incoming calls so the call queue is a great add-on to manage these kind of calls.
While the caller is waiting in the queue, custom music is played and maybe some advertising messages too. As the caller moves up the queue, the caller hears a notification informing them of their waiting time and position they are in the queue. When an agent becomes available or the caller reaches number one in the call queue, the caller is put through to the next available agent.