A method and apparatus are described for transmitting service request messages in a congested network. In one embodiment, a message including a timer value may be received by a wireless transmit/receive unit (WTRU) having a timer that is set based on the timer value. Once the timer is activated, the WTRU may not attempt to transmit a service request message to a network for mobile originated (MO) services, except for MO emergency calls, until the timer expires. In another embodiment, the timer may be deactivated in response to receiving a page for a mobile terminated (MT) call. The congested network may include a mobility management entity (MME) and a mobile switching center (MSC)/visitor location register (VLR). The MME may apply a congestion control criteria to the WTRU based on whether a timer in the MME is activated or expired.