A method is described for processing a request by server of a multimedia IP network core, the request issued by a first device registered with a first multimedia IP network core and destined for a public identity allocated to at least one second device. The method includes replication of the request as a first request and at least one second request; triggering a routing of the first request within the first multimedia IP network core; and triggering a routing of the at least one second request according to at least one predetermined route destined for at least one entity for interconnection of the first multimedia IP network core with a second network core distinct from the first multimedia IP network core.