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11.7 SIGNALING PROCEDURES FOR FAILED SETUPS 317this parameter is the same as that of Q.931 information element IE.6 (Section10.3.4). Originating exchange P bases its treatment of the calling TE on the valueof Par.9, which can indicate “user busy,” “alerting, no answer,” and so on.On 64-kb/s calls, exchange P does not provide in-band information and thecalling TE receives failure treatment FT2 (Section 10.6.1). On speech and3.1-kHz audio calls, the treatment may require that exchange P provide in-bandinformation (busy- or reorder-tone) to the calling TE (failure treatment FT2-IB).On some failure of speech and 3.1-kHz audio calls, terminating exchange R providesringing-tone, or an announcement, to the calling TE. Figure 11.7-2 shows theprocedure for the case that the exchange has determined that the called number is notassigned. The exchange connects trunk T 2 to an announcement source and sends anACM message that includes a Par.9 with location and cause values “public networkserving the remote user” and “unassigned number.” The message also includes aPar.18 (optional backward call indicators) with value “in-band tone or announcementnow available.”Originating exchanges P then gives treatment FT2-IB to the calling TE and, whenthe TE responds with a DISC message, starts the release of the network connection.11.7.2 Calls Originated by Subscribers, ISUP SignalingAll the WayIf the calling party is a subscriber, the procedures at the terminating exchange R are,with minor exceptions, as described above for speech or 3.1-kHz audio calls. Oncalls where the calling subscriber should hear busy-tone or reorder-tone, exchangeFigure 11.7-2. Unassigned number received by exchange R, on a speech or 3.1 kHz audio call.