The present invention relates to a message-based notifying method for notifying a waiting queue and an application server, wherein the method includes: sending, by a calling terminal, a call request to a called terminal; forwarding, by an application server, to the called terminal the call request sent from the calling terminal, and determining from a response message returned from the called terminal whether the called terminal is in an idle status; and if the called terminal is in a busy status, then adding by the application server the calling terminal into a waiting enqueuing queue of the called terminal, and sending to the calling terminal a waiting notification message containing a waiting queue value corresponding to the calling terminal; or if the called terminal is in an idle status, then establishing directly a communication connection between the calling terminal and the called terminal.