An application server invocated terminating service is enabled in an IMS based communication network. A request-to-establish message is received by an application server in a terminating part of the network, initiated by a calling party associated to an originating part of the network. The request-to-establish message is supplemented with information that the terminating service is desired to a called party associated to the terminating part, before being transmitted to an access node to which the called party is associated. A called terminal used by the called party is then notified that the terminating service is applicable by the access node, before the application server is confirmed that the called terminal has been notified. Supplementing the request-to-establish message in this way, enables parties communicating over an IMS based network to use the terminating service, regardless of whether they are directly associated to the network or via a non-IMS based communications network.