A CDMA communication system transmits packet data via a designated forward channel which uses a particular spreading code, in the case where a base station has the packet data to send to a mobile station while the mobile sation does not have a dedicated channel established. A base station includes a first channel transmitter for transmitting a control message including information representative of a spreading code for designating a specific forward common channel to a specific mobile station, to the mobile station via a forward common channel, and a second channel transmitter for spreading user data with the spreading code upon reception of a response to the control message and transmitting the spread user data. A mobile station includes a control message analyzer for analyzing a message including information representative of a designated spreading code received via a forward common channel, and a forward common channel receiver for despreading user data spread with the designated spreading code generated based on the information, using the spreading code.