A method for establishing a roaming connection of a communication terminal of a foreign communication network in a visited communication network , the foreign communication network and the visited communication network each comprising a plurality of sub-networks , wherein an identification entity for identification of a communication terminal is arranged in each sub-network of the visited communication network , wherein a sub-network identifier (SubNW-ID1, SubNW-ID2, SubNW-IDn) is assigned to each sub-network of the respective communication network , wherein in the visited communication network , a network management entity is arranged which manages assignment of sub-networks to communication devices , the method comprising the following steps: receiving , by a first identification entity of a first sub-network of the visited communication network , a roaming connection request from the communication terminal of the foreign communication network , the roaming connection request having an identifier (UE-ID) of the communication terminal ; identifying , by the first identification entity of the visited communication network , the communication terminal based on the identifier (UE-ID) of the communication terminal ; requesting and receiving a foreign sub-network identifier (SubNW-IDx) of a foreign sub-network of the foreign communication network by the first identification entity of the visited communication network from a foreign management entity of the foreign communication network ; verifying, by the network management entity or by the first identification entity , based on the foreign sub-network identifier (SubNW-IDx), whether a respective sub-network of the visited communication network corresponds to the foreign sub-network indicated by the foreign sub-network identifier (SubNW-IDx); and sending , by the first identification entity or the network management entity of the visited communication network , a configuration request (Cfg-Req) for a configuration of the foreign sub-network to the foreign communication network in case no respective sub-network of the visited communication network corresponds to the foreign sub-network . receiving , by a first identification entity of a first sub-network of the visited communication network , a roaming connection request from the communication terminal of the foreign communication network , the roaming connection request having an identifier (UE-ID) of the communication terminal ; identifying , by the first identification entity of the visited communication network , the communication terminal based on the identifier (UE-ID) of the communication terminal ; requesting and receiving a foreign sub-network identifier (SubNW-IDx) of a foreign sub-network of the foreign communication network by the first identification entity of the visited communication network from a foreign management entity of the foreign communication network ; verifying, by the network management entity or by the first identification entity , based on the foreign sub-network identifier (SubNW-IDx), whether a respective sub-network of the visited communication network corresponds to the foreign sub-network indicated by the foreign sub-network identifier (SubNW-IDx); and sending , by the first identification entity or the network management entity of the visited communication network , a configuration request (Cfg-Req) for a configuration of the foreign sub-network to the foreign communication network in case no respective sub-network of the visited communication network corresponds to the foreign sub-network . <EOS>