The invention relates to a method for the transmission of multimedia messages in a communication system from a transmitting terminal (MS1) to a receiving terminal (RH, MS2). The communication system comprises at least a first communication network (NW1), a second communication network (NW2) and a multimedia message switching centre (MMSC). In the first communication network (NW1), at least a first address type is used as the terminal address, and in the second communication network (NW2), at least a second address type is used as the terminal address. In the method, the address of the receiving terminal (RH, MS2) is annexed to said multimedia message. The multimedia message is further supplemented with data on the type of said address, wherein the multimedia message is transmitted from the transmitting terminal (MS1) to said multimedia message switching centre (MMSC), in which the type of the address of the receiving terminal (RH, MS2) is examined, and said address type is used to select the communication network (NW1, NW2) to be used in the transmission of the message from the multimedia message switching centre (MMSC) to the receiving terminal (RH, MS2).