The present invention relates to a method of informing an agent of a follow-up call to the agent from a telephone subscriber comprised of on receiving the follow-up call from the telephone subscriber, detecting that the agent is busy, storing a callback number of the telephone subscriber, storing at least part of a message provided by the telephone subscriber in association with the callback number, determining the identity of a specific agent to which the call is to be directed, and routing the message and the callback number to the specific agent when the specific agent becomes free.