Section: 5.5.3.1 Status enquiry procedure
Content: Whenever a call control entity wishes to check the call state of its peer entity, it may initiate the status enquiry procedure. NOTE: This may, in particular, apply to procedural error conditions described in clause 8. A call control entity initiates the status enquiry procedure by sending the STATUS ENQUIRY message and starting timer T322. The value of T322 is implementation dependent in the MS and set in the network by the network operator. While timer T322 is running, the call control entity shall not send further STATUS ENQUIRY messages. Upon receipt of a STATUS ENQUIRY message, the receiver shall respond with a STATUS message, reporting the current call state and cause value #30 "response to STATUS ENQUIRY". Receipt of the STATUS ENQUIRY shall not result in a state change relating to any protocol and connection of the receiver. If a STATUS message is received that contains cause value #30 "response to status enquiry", timer T322 shall be stopped and further appropriate actions taken, based on the information in that STATUS message, relative to the current state of the receiver of the STATUS message. These further "appropriate actions" are implementation dependent. However, the actions prescribed in subclause 5.5.3.2 shall apply. If a clearing message is received while timer T322 is running, timer T322 shall be stopped, and call clearing shall continue. If timer T322 expires, the STATUS ENQUIRY message may be retransmitted maximally once. If T322 expires after the STATUS ENQUIRY has been transmitted the maximum number of times, clearing of the call shall be initiated with cause value #41, "temporary failure", in the first call clearing message.