A computer implemented method of selective transmission of a communications message from a home telecommunications network to a visited telecommunications network for delivery to a subscriber device roaming via the visited network includes receiving the message at the home network; identifying a communications component of the visited network to which the messages is to be routed; defining an input vector for a classifier, the input vector encoding parameters of the communications component; executing the classifier to classify the communications component to determine a reliability state of the communications component; and forwarding the message to the communications component of the visited network for delivery to the subscriber device in dependence on the classified reliability state.