| 摘要 |
PURPOSE: A method for providing a call processing service in a call congested state is provided to allow a user to inform his/her intension to the other party even if a traffic channel is not available for allocation due to contested traffic. CONSTITUTION: After an MSC sends a call proceeding message to an MS(Mobile Station), resource reservation is made between an RNC and the MSC. The MSC reserves a VPI(Virtual Path Identifier) and a VCI(Virtual Channel Identifier)(750). Thereafter, the MSC transmits an RAB(Radio Access Bearer) allocation request message(RAB Assignment Req) to the RNC and waits a CID(Channel Identifier) of an AAL2 from the RNC. The MSC receives an RAB allocation response message(RAB Assignment Rsp) informing that 'channel resources are not available for use' and makes the reserved resources(VPI,VCI) be available resources(760). And then, without releasing a call, the MSC transmits a facility message including information that the call is not connected due to shortage of resources and an SMS can be attempted instead to the MS. The MS sends a message informing that a call cannot be performed due to shortage of resources because traffic is saturated by a user interface through its own application layer. If the user does not want the SMS transmission but want to terminate the call as it is, it sends a disconnection message(Disconnect) to the MSC.
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