A method for intersystem transfer of calls from a first cellular mobile radio system using the macrodiversity transmission technique to a second cellular mobile radio system, the macrodiversity transmission using a radio network controller of the first system, referred to as the serving controller, and at least one other radio network controller of the first system, referred to as the drift controller, wherein adjoining cell information relating to the second system is signaled to the serving controller by at least one drift controller controlling at least one serving cell belonging to the first system and having at least one adjoining cell belonging to the second system.