IMG 1010 - SIP Redirect - IW Call Diversion Info to SS7
When a call is Redirected (also known as Call Forwarding), the called party redirects the call to a third party. The redirecting could be the result of the line being busy, the called party configured for call forwarding, or a host of other reasons. When the call is redirected, the ACM and/or CPG backward call messages will be mapped back to the SIP leg in either the Diversion or History-Info headers. The parameters that will be mapped are displayed in the table below.
Backward Call Messages |
Address Complete Message (ACM)
Call Progress Message (CPG)
|
These parameters are all mapped back to the SIP leg. Refer to the Call Flow diagrams below as to when and how they are mapped.
Call Flow Diagrams
The first call flow below displays one scenario of a call being Redirected from an SS7 User to an ISDN User. The call flows to follow display the mappings from the SS7 backward call messages to SIP mappings.
Call Flow 1 - Basic Redirecting Scenario
In the Call Flows below, the call is first sent to the SS7 User. The SS7 User is configured to redirect the call to the Redirected User and redirects the call. The SS7 User also sends either an ACM or CPG message in the backward direction with the redirection information. The parameters in the ACM or CPG message will determine how the redirecting information will be mapped back to the original SIP User. Also, the IMG can be configured to map the parameters back to the SS7 User in either the SIP Diversion Header or SIP History-Info Header.
Call Flow 2 - ACM mapped to 183 Progress
Information in the backward ACM message |
In the scenario where all of the parameters in the bulleted list below are received in the backward ACM message:
The parameters received are mapped to either the Diversion Header or the History-Info Header in the 183 Session Progress message. Refer to the call flow diagram below. For individual parameter mappings, refer to the Diversion and History-Info Mappings section in this topic. |
Call Flow 3 - ACM mapped to 180 Ringing
Information in the backward ACM message |
In the scenario where all of the parameters in the bulleted list below are received in the backward ACM message.
The parameters received are mapped to either the Diversion Header or the History-Info Header in the 180 Ringing message. Refer to the call flow diagram below. For individual parameter mappings, refer to the Diversion and History-Info Mappings section in this topic. |
Call Flow 4 - CPG mapped to 183 Progress
Information in the backward CPG message |
In the scenario where the Event parameter includes either the CFB, CFNR, or CFU along with both the Redirection Number and Call Diversion Information in the backward CPG message. See list below.
The parameters received are mapped to either the Diversion Header or the History-Info Header in the 183 Progress message. Refer to the call flow diagram below. For individual parameter mappings, refer to the Diversion and History-Info Mappings section in this topic. |
Call Flow 5 - CPG mapped to 183 Progress
Information in the backward CPG message |
In the scenario where the Event parameter includes either the CFB, CFNR, or CFU but does not include the Redirection Number or the Call Diversion Information in the backward CPG message. See list below.
The parameters received are mapped to either the Diversion Header or the History-Info Header in the 183 Progress message with Default Values. Refer to the call flow diagram below. For individual parameter mappings, refer to the Diversion and History-Info Mappings section in this topic. |
Call Flow 6 - CPG mapped to 180 Ringing
Information in the backward CPG message |
In the scenario where the Event parameter is set to Alerting and either the Redirection Number, the Call Diversion Information or both are included in the backward CPG message. See list below.
The parameters received are mapped to either the Diversion Header or the History-Info Header in the 180 Ringing message. Refer to the call flow diagram below. For individual parameter mappings, refer to the Diversion and History-Info Mappings section in this topic. |
Call Flow 7 - CPG mapped to 180 Ringing without Diversion/History-Info Header
Information in the backward CPG message |
In the scenario where the Event parameter is set to Alerting and neither the Redirection Number, nor the Call Diversion Information are included in the backward CPG message. See list below.
The parameters received NOT mapped to the Diversion or History-Info Header. Refer to the call flow diagram below. |
Call Flow 8 - CPG mapped to 183 Progress
Information in the backward CPG message |
In the scenario where the Event parameter is set to Progress and either the Redirection Number, the Call Diversion Information or both are included in the backward CPG message. See list below.
The parameters received are mapped to either the Diversion Header or the History-Info Header in the 183 Progress message. Refer to the call flow diagram below. For individual parameter mappings, refer to the Diversion and History-Info Mappings section in this topic. |
Call Flow 9 - CPG mapped to 183 Progress
Information in the backward CPG message |
In the scenario where the Event parameter is set to Progress and neither the Redirection Number, nor the Call Diversion Information are included in the backward CPG message. See list below.
The parameters received NOT mapped to the Diversion or History-Info Header. Refer to the call flow diagram below. |
Diversion and History-Info Mappings SS7 to SIP
As described above, the parameters in the ACM and CPG backward messages can be mapped to either the SIP Diversion Header or the SIP History-Info Header. Below are tables displaying how the parameters in the ACM and CPG messages are mapped to the SIP Diversion and SIP History-Info Headers.
Diversion Header Mappings
The IMG implementation of SIP Diversion Header is compatible with RFC 5806.
Call Diversion Info
| Parameters in ACM/CPG | Diversion Header Parameters |
Notification Subscription Options |
|
|
| Unknown | privacy=off |
| Presentation Not Allowed | privacy=full |
| Presentation Allowed with Redirection Number | privacy=off |
| Presentation Allowed without Redirection Number | privacy=off |
Redirecting Reason |
|
|
| Unknown/ Not Available | reason=unknown |
| User Busy | reason=user busy |
| No Reply | reason=no answer |
| Unconditional | reason=unconditional |
| Deflection During Alerting | reason=deflection during alerting |
| Deflection Immediate Response | reason=deflection immediate response |
| Mobile Subscriber Not Reachable | reason=unknown |
| Call Forwarding DTE Out of Order | reason=unavailable |
| Call Deflection or Call Forwarding by the Called DTE | reason=deflection |
| Call Forwarding Unconditional or Systematic Call Redirection | reason=unconditional |
Redirecting Number
| Parameters in ACM/CPG | Diversion Header Parameters |
Nature of Address ind=x |
| noa=x |
Address Signals | 1234 | username=1234 |
| Not Available | unknown@unknown.invalid |
|
| counter=1 (By Default) |
History-Info Header Mappings
Call Diversion Info
| Parameters in ACM/CPG | History-Info Header Parameters |
Notification Subscription Options |
|
|
| Unknown | privacy=none or absent |
| Presentation Not Allowed | privacy=history |
| Presentation Allowed with Redirection Number | privacy=none or absent |
| Presentation Allowed without Redirection Number | privacy=none or absent |
Redirecting Reason |
|
|
| Unknown/ Not Available | cause=404 |
| User Busy | cause=486 |
| No Reply | cause=408 |
| Unconditional | cause=302 |
| Deflection During Alerting | cause=302 |
| Deflection Immediate Response | cause=302 |
| Mobile Subscriber Not Reachable | cause=503 |
Redirecting Number
| Parameters in ACM/CPG | Diversion Header Parameters |
Nature of Address ind=x |
| noa=x |
Address Signals |
| username |
Configuration
There is no additional configuration needed for the functionality described above.