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5.11.1.2 Exceptional procedures

The procedures of 5.8 shall apply, with the addition that:

a) If the calling user receives no Bearer capability information element in the CONNECT message, or prior to the CONNECT message in some other call control message, the user shall assume that the bearer service or teleservice corresponds to the first Bearer capability information element that the user included in the SETUP message.

b) If the calling user receives a Progress indicator information element with a progress description No. 1, call is not end-to-end ISDN, further call progress information may be available in-band or progress description No. 2, destination address is non-ISDN subsequent to a Progress indicator information element with a progress description No. 5, interworking has occurred and has resulted in a telecommunication service change, then the last received Progress indicator information element shall be taken account of. Where the progress description is No. 1, call is not end-to-end ISDN, further call progress information maybe available in-band or progress description is No. 2, destination address is non-ISDN the user shall assume a bearer service category of circuit-mode 64 kbit/s 8 kHz structured usable for 3.1 kHz audio information transfer.

c) If the calling user includes a Low layer compatibility information element in a SETUP message containing a repeated Bearer compatibility information element, even though this is
an error condition, the network shall continue normal call handling, i.e. transport the Low layer compatibility information element transparently across the network.

d) If the calling user receives a call control message other than the CONNECT message containing a Bearer capability information element but without a Progress indicator information element, with progress description No. 5, interworking has occurred and has resulted in a telecommunication service change, the calling user shall handle the call in the normal manner.

e) If the calling user receives no Bearer capability information element in a call control message other than CONNECT but the Progress indicator information element, with progress description No. 5, interworking has occurred and has resulted in a telecommunication service change, present, the calling user shall assume that the bearer service or teleservice corresponds to the first Bearer capability information element that was included in the SETUP message.