A method of facilitating the interworking of network elements of one or more communication networks some of which network elements support a given security mechanism and others of which do not. The method comprises, at each network element which does support the security mechanism, maintaining a database listing peer network elements and an indication of whether or not the peer network elements support the security mechanism. Upon initiation of a signalling communication from a peer network element supporting the security mechanism to another peer network element, inspecting the database of the initiating network element to determine whether or not the peer network element supports the security mechanism, and conducting the communication accordingly. The databases 9 stored at network elements are updated dynamically based upon signalling information received from peer network elements. The method ensures that the security mechanism for securing communications between elements is used when the mechanism is available.