A method for barring access in a mobile device network, the method being performed in a radio access network, RAN, node and comprising: implementing an access class barring, ACB, function specifying a device type to be barred, wherein a device of the device type to be barred is a Machine-to-Machine, M2M, type device, the implementing comprising: - selecting an access class to be barred; - transmitting, when a particular cell is overloaded, an ACB command to active mobile devices of the device type, wherein -- the ACB command is a System Information Block Type 2, SIBType2, message comprising i) the access class to be barred and ii) access class barring values specific for the device type; receiving an access request from a mobile device in the mobile network; and processing the received access request in accordance with the implemented ACB function, the processing comprising: - determining whether the device type specified in the ACB function matches a device type of the requesting mobile device; - if so, determining whether the ACB Function specifies an access class matching an access class allocated to the requesting mobile device; - if so, determining if the ACB function specifies another exception that is met by the requesting mobile device; - if the ACB function does not specify another exception that is met by the requesting mobile device, determining whether the ACB function operates probabilistically: -- if the ACB function is not probabilistic, rejecting a connection for the requesting mobile device; -- if the ACB function is probabilistic, executing a probabilistic test, and if the test fails, rejecting the connection for the requesting mobile device. implementing an access class barring, ACB, function specifying a device type to be barred, wherein a device of the device type to be barred is a Machine-to-Machine, M2M, type device, the implementing comprising: - selecting an access class to be barred; - transmitting, when a particular cell is overloaded, an ACB command to active mobile devices of the device type, wherein -- the ACB command is a System Information Block Type 2, SIBType2, message comprising i) the access class to be barred and ii) access class barring values specific for the device type; - selecting an access class to be barred; - transmitting, when a particular cell is overloaded, an ACB command to active mobile devices of the device type, wherein -- the ACB command is a System Information Block Type 2, SIBType2, message comprising i) the access class to be barred and ii) access class barring values specific for the device type; receiving an access request from a mobile device in the mobile network; and processing the received access request in accordance with the implemented ACB function, the processing comprising: - determining whether the device type specified in the ACB function matches a device type of the requesting mobile device; - if so, determining whether the ACB Function specifies an access class matching an access class allocated to the requesting mobile device; - if so, determining if the ACB function specifies another exception that is met by the requesting mobile device; - if the ACB function does not specify another exception that is met by the requesting mobile device, determining whether the ACB function operates probabilistically: -- if the ACB function is not probabilistic, rejecting a connection for the requesting mobile device; -- if the ACB function is probabilistic, executing a probabilistic test, and if the test fails, rejecting the connection for the requesting mobile device. - determining whether the device type specified in the ACB function matches a device type of the requesting mobile device; - if so, determining whether the ACB Function specifies an access class matching an access class allocated to the requesting mobile device; - if so, determining if the ACB function specifies another exception that is met by the requesting mobile device; - if the ACB function does not specify another exception that is met by the requesting mobile device, determining whether the ACB function operates probabilistically: -- if the ACB function is not probabilistic, rejecting a connection for the requesting mobile device; -- if the ACB function is probabilistic, executing a probabilistic test, and if the test fails, rejecting the connection for the requesting mobile device. -- if the ACB function is not probabilistic, rejecting a connection for the requesting mobile device; -- if the ACB function is probabilistic, executing a probabilistic test, and if the test fails, rejecting the connection for the requesting mobile device.