A user equipment for handling an attach procedure with a service network is provided. The user equipment comprises a wireless module transmitting an attach request message to the service network and receiving an attach accept message replied to the attach request message from the service network, and a controller determining whether to accept the attach accept message, sending an attach complete message, via the wireless module, to the service network in response to the attach accept message being accepted, and resending the attach request message, via the wireless module, to the service network in response to the attach accept message not being accepted.