According to the invention, a reduced set of transport format combinations is signalled to a subscriber station which has established a link to a second radio communication system in a second signalling channel of said second radio communication system. The transport format indicator is then selected from the reduced set of transport format combinations and used to initiate a link transfer to the first signalling channel of a first radio communication system. A full set of transport format combinations is subsequently signalled to the subscriber station in the first signalling channel.