An intelligent communications network having a distributed arrangement of service components which perform call processing by distributed processing involving the sending of requests, wherein each service component comprises:
- storage means for storing an associated preassigned service element parameter (SEP);
- means for generating requests including an SEP field;
- means for writing to the SEP field of each generated request the associated SEP, together with, in the event that a said generated request is generated in response to receipt at the service component of a request sent from another service component, the contents of the SEP field of the received request;
- means for detecting when the service component is in overload state;
- and
- means for determining, while the service component is in overload state, the extent of the processing of a request newly received thereat in dependence upon the contents of the SEP field of said newly received request.