A method of controlling a backoff timer at a user equipment (UE) configured for dual priority, the method includes transmitting a non access stratum (NAS) request message without an access point name (APN) including a low priority indicator set to a first value to a network node, wherein the first NAS request message without the APN is an attach request message transmitted along with a packet data network (PDN) connectivity request without the APN; receiving a reject message for the NAS request message from the network node, and wherein a cause in the reject message is set to insufficient resources; setting the low priority indicator to a second value; and initiating a new attach procedure without the APN, while a session management (SM) backoff timer is running, wherein the first value of the low priority indicates that the UE is configured for NAS signaling low priority.