A method of controlling a local process that forms part of a first processing entity such as a signalling gateway , said first processing entity maintaining a plurality of associations with a plurality of remote processes in a second processing entity such as a application server. The method comprises the steps of: receiving a failure message from a remote process indicating a fault affecting an association linking the local process with that remote process; queueing data messages destined for that remote process; controlling the transmission of an acknowledgement of the failure message so that data messages pending on the association are received at that remote process before the acknowledgment of the failure message; and initiating a traffic diversion to set up an alternate path between said first processing entity and said second processing entity for queued data messages. The local processes can be signalling gateway processes having a common point code or set of point codes and the remote processes can be application server processes having a common routing key.