10.5.3_SP8 - An Overview of Features
F-5948 Mapping ISDN Call Proceeding to SIP 183
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Before the introduction of Feature F-5948, interworking the ISDN Call Proceeding message to the SIP leg was based on draft-kotar-sipping-dss1-sip-iw-01.txt section 7.3.2. The receipt of a DSS1 CALL PROCEEDING message SHALL NOT result in any SIP message being sent. With the introduction of F-5948, the Call Proceeding message from the ISDN side will be interworked into a 183 Session Progress with SDP message when the value of the Progress Indicator parameter in the Call Proceeding message is either "1" or "8". By interworking these parameters, an early voice path can be established so the caller can hear a prompt played by the terminating endpoint. If no progress indicator is present or the value of the ISDN Progress Indicator is not "1" or "8" then the call will proceed as normal. The Call Proceeding message will be dropped and no SIP 183 Session Progress will be sent. Refer to the topics in the links below for more information.
Related Topics:
IMG 1010 - SIP_ISDN Interworking
IMG 1010 - Map ISDN Call Proceeding to SIP 183
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