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