A method comprising: detecting (214, 310), by a base station, a failure of an interface between the base station and a core network (151, 143) sending (216, 320), by the base station, during a transition period in which the base station operates and continues operating in a normal cellular or infrastructure mode, a notification message to one or more mobile stations of a cell indicating the failure of the base station-core network interface; and performing, by the base station, either a first set of operations or a second set of operations, depending on base station's capabilities or requests from the mobile stations, the first set of operations comprising; selecting (234, 330), by the base station, within the transition period, a new mode of operation for the base station, the new mode of operation for the base station including at least one of the following: to cease operating or a non-operational mode; and to operate in a device-to-device assistance mode of operation in which the base station assists direct mobile station-to-mobile station communications; and the second set of operations comprising: receiving, by the base station from one or more of the mobile stations in the cell, within the transition period, a device-to-device assistance request that requests the base station to assist with direct mobile station-to-mobile station communications for the cell; selecting, by the base station, within the transition period, device-to-device assistance mode of operation for the base station based on at least the one or more assistance requests; and sending, by the base station to the one or more mobile stations in the cell, a mode indication message that identifies the selected device-to-device assistance mode of operation for the base station. detecting (214, 310), by a base station, a failure of an interface between the base station and a core network (151, 143) sending (216, 320), by the base station, during a transition period in which the base station operates and continues operating in a normal cellular or infrastructure mode, a notification message to one or more mobile stations of a cell indicating the failure of the base station-core network interface; and performing, by the base station, either a first set of operations or a second set of operations, depending on base station's capabilities or requests from the mobile stations, the first set of operations comprising; selecting (234, 330), by the base station, within the transition period, a new mode of operation for the base station, the new mode of operation for the base station including at least one of the following: to cease operating or a non-operational mode; and to operate in a device-to-device assistance mode of operation in which the base station assists direct mobile station-to-mobile station communications; and the second set of operations comprising: receiving, by the base station from one or more of the mobile stations in the cell, within the transition period, a device-to-device assistance request that requests the base station to assist with direct mobile station-to-mobile station communications for the cell; selecting, by the base station, within the transition period, device-to-device assistance mode of operation for the base station based on at least the one or more assistance requests; and sending, by the base station to the one or more mobile stations in the cell, a mode indication message that identifies the selected device-to-device assistance mode of operation for the base station. to cease operating or a non-operational mode; and to operate in a device-to-device assistance mode of operation in which the base station assists direct mobile station-to-mobile station communications; and the second set of operations comprising: receiving, by the base station from one or more of the mobile stations in the cell, within the transition period, a device-to-device assistance request that requests the base station to assist with direct mobile station-to-mobile station communications for the cell; selecting, by the base station, within the transition period, device-to-device assistance mode of operation for the base station based on at least the one or more assistance requests; and sending, by the base station to the one or more mobile stations in the cell, a mode indication message that identifies the selected device-to-device assistance mode of operation for the base station. receiving, by the base station from one or more of the mobile stations in the cell, within the transition period, a device-to-device assistance request that requests the base station to assist with direct mobile station-to-mobile station communications for the cell; selecting, by the base station, within the transition period, device-to-device assistance mode of operation for the base station based on at least the one or more assistance requests; and sending, by the base station to the one or more mobile stations in the cell, a mode indication message that identifies the selected device-to-device assistance mode of operation for the base station.