Communication system between a radio communication network and a connectionless network and interworking apparatus for use in the communication system

In an interworking apparatus operable in accordance with a radio protocol of using a plurality of radio channels in parallel and another protocol different from the radio protocol, a plurality of memories store a plurality of frames one by one in correspondence with the plurality of the radio channels, respectively. The memories may be for storing PPP frames and/or radio frames. The interworking apparatus may be included in a mobile station or an interworking facility, such as a base station, a mobile switching center. Without exerting any influence to the other radio channels prior to transmission, reception can be done by using no order control protocol. This is very effective and helpful to improve in the transmission efficiency.