A method of Radio Resource Control, RRC, connection resumption, implemented in a Radio Access Network, RAN, for use with a mobile device, the method comprising: sending, by a first RAN node of the RAN, a connection suspend command message to a mobile device, the connection suspend command message instructing the mobile device to suspend an RRC connection between the mobile device and the first RAN node by: causing storage of RRC connection data for the RRC connection which is being suspended between the mobile device and the first RAN node, and causing release of radio resources associated with the RRC connection which is being suspended between the mobile device and the first RAN node, wherein user plane communications between the mobile device and the RAN are disabled until receipt of an RRC connection resume request by the RAN from the mobile device, and wherein the mobile device is able to receive paging from the RAN while the RRC connection is suspended; and receiving, at a second RAN node of the RAN, 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. sending, by a first RAN node of the RAN, a connection suspend command message to a mobile device, the connection suspend command message instructing the mobile device to suspend an RRC connection between the mobile device and the first RAN node by: causing storage of RRC connection data for the RRC connection which is being suspended between the mobile device and the first RAN node, and causing release of radio resources associated with the RRC connection which is being suspended between the mobile device and the first RAN node, wherein user plane communications between the mobile device and the RAN are disabled until receipt of an RRC connection resume request by the RAN from the mobile device, and wherein the mobile device is able to receive paging from the RAN while the RRC connection is suspended; and causing storage of RRC connection data for the RRC connection which is being suspended between the mobile device and the first RAN node, and causing release of radio resources associated with the RRC connection which is being suspended between the mobile device and the first RAN node, wherein user plane communications between the mobile device and the RAN are disabled until receipt of an RRC connection resume request by the RAN from the mobile device, and wherein the mobile device is able to receive paging from the RAN while the RRC connection is suspended; and receiving, at a second RAN node of the RAN, 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.