A method of handling a RRC connection resume procedure between a first layer and a second layer of a communication device, the method comprises the first layer in a first idle mode with suspend indication transmit a first request message for resuming a RRC connection and at least one first identity parameter to the second layer, after receiving a suspend indication from the second layer; the second layer transmit the RRC connection resume request message to the network, after receiving the first request message from the first layer; the second layer receive a first RRC connection setup message from the network, after transmitting the RRC connection resume request message to the network; and the second layer transmit a first RRC connection setup complete message comprising the at least one first identify parameter to the network, after receiving the first RRC connection setup message from the network.