The invention relates to a communication system (300) for the communication in a communication network (303), wherein the communication network (303) has a first sub-network (307) and a second sub-network (311), comprising: a first identification entity (309), which is associated with the first sub-network (307) and is designed to receive an identity (302) of a communication terminal (301) and to identify the communication terminal (301) on the basis of the identity (302) for the communication via the first sub-network (307); a second identification entity (313), which is associated with the second sub-network (311) and is designed to receive the identity (302) of the communication terminal (301) and to identify the communication terminal (301) on the basis of the identity (302) for the communication via the second sub-network (311); and a management entity (319), which is designed to authenticate the communication terminal (301) for the communication via the particular sub-network (307, 311).
