In a SIP to ISDN call, for the IMG 2020 to play Call Progress Tones / Ring Back, the outgoing channel group pane must have the Ingress Side will play Call Progress Tones field set to True. In this state, the Call Progress Tones / Ring Back will be played unconditionally. Equally, if the Ingress Side will play Call Progress Tones field is set to False in the outgoing channel group, the Call Progress Tones / Ring Back will not be played. See the Call Flow Diagrams below which highlight the functionality.
FR16176 feature adds an additional rule regarding when the Call Progress Tones / Ring Back is being stopped.
This feature is supported from SIP to ISDN and from SIP to SS7.
Call Flow Diagrams
SIP to ISDN
When the field Ingress side will play Call Progress Tones is set to true and the egress ISDN side receives an Alerting or Progress message without progress indicator No. 1 or No. 8, the IMG 2020 will play Ring Back to the Ingress SIP side. See below.
SIP to ISDN
When the field Ingress side will play Call Progress Tones is set to true and the egress ISDN side receives an Alerting message without progress indicator No. 1 or No. 8, the IMG 2020 will play Ring Back to the Ingress SIP side. The Ring Back will be STOPPED if the egress ISDN side receives a Progress message with progress indicator No. 1 or No. 8. See below.
SIP to ISDN
When the field Ingress side will play Call Progress Tones is set to true and the egress ISDN side receives an Alerting or Progress message with progress indicator No. 1 or No. 8, the IMG 2020 will NOT play Ring Back to the Ingress SIP side. See below.
SIP to SS7
When the field Ingress side will play Call Progress Tones is set to true and the egress SS7 side receives an SS7 ACM message with progress indicator No. 1 or No. 8, the IMG 2020 will not play Ring Back to the Ingress SIP side. See below.
SIP to SS7
When the field Ingress side will play Call Progress Tones is set to true and the egress SS7 side receives an SS7 Call Progress (CPG) message which contains Optional Backward Call Indicators (OBCI) with inband info or appropriate pattern available the IMG 2020 will not play Ring Back to the Ingress SIP side. See below.
SIP to SS7
When the field Ingress side will play Call Progress Tones is set to true and the egress SS7 side receives an SS7 Call Progress (CPG) message which contains Optional Backward Call Indicators (OBCI) with inband info or appropriate pattern available the IMG 2020 will not play Ring Back to the Ingress SIP side. See below.
SIP to SS7
When the field Ingress side will play Call Progress Tones is set to true and the egress SS7 side receives an SS7 ACM message which does not contain Optional Backward Call Indicators (OBCI) with inband info or appropriate pattern available the IMG will play Ring Back to the Ingress SIP side. The Ring Back will be STOPPED if the egress SS7 side receives an SS7 Call Progress (CPG) message which does contain Optional Backward Call Indicators (OBCI) with inband info or appropriate pattern available. See below.
Below is a table for easy reference displaying the different states.
SIP | ISDN | Ingress side will play CPT = True |
183 Session Progress | Alerting with PI=#1 or #8 | CPT / Ring Back NOT Played |
183 Session Progress | Progress with PI=#1 or #8 | CPT / Ring Back NOT Played |
183 Session Progress | Alerting without PI=#1 or #8 | CPT / Ring Back Played |
183 Session Progress | Progress without PI=#1 or #8 | CPT / Ring Back Played |
SIP | SS7 | Ingress side will play CPT = True |
183 Session Progress | ACM w/ATP. PI=#1 or #8 | CPT / Ring Back NOT Played |
183 Session Progress | ACM w/OBCI. PI=#1 or #8 | CPT / Ring Back NOT Played |
183 Session Progress | CPG w/OBCI. PI=#1 or #8 | CPT / Ring Back NOT Played |