A method of Radio Resource Control, RRC, connection resumption implemented in a Radio Access Network, RAN, comprising a first RAN node and a second RAN node for use with a mobile device, the method comprising: the first RAN node suspending an RRC connection with the mobile device, wherein suspending the RRC connection comprises: the first RAN node sending a connection suspend command message to the mobile device instructing the mobile device to suspend the RRC connection, the first RAN node storing RRC connection data of the RRC connection which is being suspended, and the first RAN node releasing radio resources associated with the RRC connection, which is being suspended between the first RAN node and the mobile device, after sending the connection suspend command message to the mobile device; the first RAN node transmitting RRC connection data, relating to the suspended RRC connection with the mobile device, to a Mobility Management Entity, MME, for storage at the MME; the second RAN node receiving from the mobile device an RRC connection resume message comprising a request to resume the suspended RRC connection, wherein the RRC connection resume message includes: an identifier of the first RAN node where the RRC connection was suspended; and a Short MAC-I derived using parameters relating to the first RAN node where the RRC connection was suspended. the first RAN node suspending an RRC connection with the mobile device, wherein suspending the RRC connection comprises: the first RAN node sending a connection suspend command message to the mobile device instructing the mobile device to suspend the RRC connection, the first RAN node storing RRC connection data of the RRC connection which is being suspended, and the first RAN node releasing radio resources associated with the RRC connection, which is being suspended between the first RAN node and the mobile device, after sending the connection suspend command message to the mobile device; the first RAN node transmitting RRC connection data, relating to the suspended RRC connection with the mobile device, to a Mobility Management Entity, MME, for storage at the MME; the first RAN node sending a connection suspend command message to the mobile device instructing the mobile device to suspend the RRC connection, the first RAN node storing RRC connection data of the RRC connection which is being suspended, and the first RAN node releasing radio resources associated with the RRC connection, which is being suspended between the first RAN node and the mobile device, after sending the connection suspend command message to the mobile device; the first RAN node transmitting RRC connection data, relating to the suspended RRC connection with the mobile device, to a Mobility Management Entity, MME, for storage at the MME; the second RAN node receiving from the mobile device an RRC connection resume message comprising a request to resume the suspended RRC connection, wherein the RRC connection resume message includes: an identifier of the first RAN node where the RRC connection was suspended; and a Short MAC-I derived using parameters relating to the first RAN node where the RRC connection was suspended. an identifier of the first RAN node where the RRC connection was suspended; and a Short MAC-I derived using parameters relating to the first RAN node where the RRC connection was suspended.