A telecommunications network includes a processor controlled switch and a network intelligence platform overload control function runs in the network intelligence layer. The overload control function measures the period of time taken to handle a call switching request and if the time taken exceeds a pre-determined quality of service threshold, it implements a call gapping function. The call gapping function modifies the gapping period such that requests to effect calls to particular destinations are spaced and any call arriving at a switching point prior to expiration of the gap period is automatically rejected by the local control processor. As the overload control function runs in a plurality of nodes, which may be file servers of the intelligence layer, the gapping period returned to the switch is dependent upon the perceived overload at the particular node. Traffic variations at the nodes may result in variations in the gapping period between nodes and therefore each node is arranged to communicate with other nodes to determine an average gapping period for the group of nodes and individual gapping periods in the nodes are relaxed towards the average value.