Method for allocating a sub-network to a communication terminal in a communication network with a plurality of sub-networks (307, 311, 315), and a base station and a management entity or only a base station, wherein one sub-network identifier (312, 314, 316) is allocated to each sub-network (307, 311, 315), with: reception, by the base station, of a connection request for establishing communication across a specified sub-network together with an identification from the communication terminal, wherein the identification comprises a sub-network-identifier of the specified sub-network of the communication network; extraction, by the base station, of the sub-network identifier from the received identification; selection, by the base station or the management entity, of the specified sub-network from the plurality of sub-networks (307, 311, 315) of the communication networks based on the extracted sub-network identifier; and allocation, by the base station or the management entity, of the specified sub-network to the communication terminal for communication in the communication network, characterized in that the identification comprises at least one of the following identifications: an International Mobile Subscriber Identity (IMSI), wherein the sub-network identifier is located in the Mobile Subscriber Identification Number Field or in the Mobile Network Code Field of the IMSI; an eID with the sub-network-identifier on an eSIM in the communication terminal; a network identifier of the communication network with the sub-network-identifier; an International Mobile Station Equipment Identity with the sub-network identifier. reception, by the base station, of a connection request for establishing communication across a specified sub-network together with an identification from the communication terminal, wherein the identification comprises a sub-network-identifier of the specified sub-network of the communication network; extraction, by the base station, of the sub-network identifier from the received identification; selection, by the base station or the management entity, of the specified sub-network from the plurality of sub-networks (307, 311, 315) of the communication networks based on the extracted sub-network identifier; and allocation, by the base station or the management entity, of the specified sub-network to the communication terminal for communication in the communication network, characterized in that the identification comprises at least one of the following identifications: an International Mobile Subscriber Identity (IMSI), wherein the sub-network identifier is located in the Mobile Subscriber Identification Number Field or in the Mobile Network Code Field of the IMSI; an eID with the sub-network-identifier on an eSIM in the communication terminal; a network identifier of the communication network with the sub-network-identifier; an International Mobile Station Equipment Identity with the sub-network identifier. an International Mobile Subscriber Identity (IMSI), wherein the sub-network identifier is located in the Mobile Subscriber Identification Number Field or in the Mobile Network Code Field of the IMSI; an eID with the sub-network-identifier on an eSIM in the communication terminal; a network identifier of the communication network with the sub-network-identifier; an International Mobile Station Equipment Identity with the sub-network identifier.