Intersystem change between different radio access networks

A method for use in a wireless terminal for use both (a) in a wireless cellular communication system comprising a radio access network (RAN) of a first type and also (b) in a wireless cellular communication system comprising a radio access network (RAN) of a second type different from the first type, each RAN comprising at least one base station, the base stations of the respective RANs being located in respective radio access cells that may be the same cell or different radio access cells, the wireless terminal being capable of being registered with a RAN of the first type and a RAN of the second type at the same time and being capable of being wirelessly connected to a RAN of either the first type or the second type in a connected state,

• the method comprising:
• when the wireless terminal is registered with both a first RAN of the first type and a second RAN of the second type and is wirelessly connected to the first RAN in the connected state,
• receiving a mobility signal via the first RAN indicating a RAN of the second type
• and, in response to receiving the mobility signal and in response to being so registered with the first RAN and second RAN,
• transmitting an access trigger signal for receipt by the second RAN, the trigger signal indicating that the wireless terminal is to be connected to the second RAN in the connected state.