Abstract: A signalling method and conversion device for telecommunications networks, for example mobile networks such as GSM or UMTS networks, wherein at least certain subscribers can register in their home network, or in a telecommunications network having a roaming agreement with the operator of their home network, using a first subscriber identification from the number area of their home operator, certain of these subscribers being assigned a second subscriber identification from the number area of a partner network operator with which these subscribers can register in a visited network with which operator their home network operator does not have a roaming agreement, the signalling traffic concerning subscribers who have been registered in such a visited network with a second subscriber identification number being conducted to the partner network, being filtered there, and being rerouted to their home network, and signalling traffic concerning such subscribers received in said partner network from said home network