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5.11.3.2.2 Exceptional procedures

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

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

b) If the network 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 may be available in-band or the progress description is No. 2 destination address is non-ISDN the network 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 a low layer compatibility information is received from the originating network for a connection request for which bearer capability selection is indicated, even though this is an error condition, the network shall include the low layer compatibility information in the Low layer compatibility information element in the SETUP message sent to the destination user.

d) If the network 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 user shall continue normal call handling, i.e. transport the Low layer compatibility information element transparently across the private network.

e) If the called user sends a Bearer capability information element in any call control message that contains an information transfer capability which is not that requested or the nominated alternative, the destination network shall clear the call using normal clearing procedures with clearing cause No. 111, protocol error, unspecified.

f) If the network receives a call control message other than a 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 bearer service change, the network shall act as if the Progress indicator information element, with progress description No. 5, interworking has occurred and has resulted in a telecommunication service change, was present and handle the call in the normal manner.

g) If the network 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 network shall assume that the bearer service or teleservice corresponds to the first Bearer capability information element that the network included in the SETUP message.