In order to secure interceptible calls end-to-end, an intermediate MIKEY server is used to allow an intermediate SIP server to communicate with a key-management server. The intermediate SIP server intercepts call elements when a call is initialized among a plurality of terminal devices. The intermediate SIP server supplies these intercepted elements to the intermediate MIKEY server, which then establishes a dialogue with the key-management server on the basis of these elements. The result of this dialogue is sent back to the intermediate SIP server, which records same as call metadata allowing direct or deferred use of the call content.