The OC-Terminating-Domain header is a custom SIP header used by Sentinel VoLTE SCC-AS to communicate information about the terminating domain to upstream nodes in a network.
This header is inserted into responses that go "upstream" (towards the calling party). This is typically used for charging purposes, as by definition the SCC-AS is the final AS in the iFC trigger chain for terminating triggers, and does not perform charging.
Therefore any other SIP AS invoked in the terminating trigger chain was invoked prior to the SCC-AS.
The SCCTADSRouting and SCCTADSParallelRouting features both add this header to all provisional and success responses for an initial INVITE
that are forwarded upstream from a terminating instance. The header will never appear on a final error response.
Header Format
The header name is OC-Terminating-Domain and its value is a simple string with no special formatting. The header does
not have any special parameters. Possible values are described below.
Example:
OC-Terminating-Domain: PS=EUTRANHeader Values
The value of the header will depend on which domain the response originated in:
-
Responses from the CS domain will always have the header value set to
CS -
Responses from the PS domain will always have the header value set to the match the String stored in the
PSTerminatingDomainHeaderValuein session state if +sip.instance routing is disabled, and otherwise will have it set to the String stored in the 'TADSPacketRoutes' in session state for the route that the response is arriving from.
The values stored in PSTerminatingDomainHeaderValue and `TADSPacketRoutes' are determined by the TADS Data Lookup feature.
Default Values
Out of the box, Sentinel VoLTE supports the following values for the OC-Terminating-Domain header:
| Value | Access Domain | Meaning |
|---|---|---|
CS |
CS |
The response was received from a leg that routed towards the Circuit Switched network. |
PS |
PS |
The response was received from a leg that was routed towards the Packet Switched network. This value is used when more specific information about the Packet Switched network is not available |
PS=EUTRAN |
PS |
Indicates terminating access is over E-UTRAN (LTE) radio network |
PS=NR |
PS |
Indicates terminating access is over NR (5G) radio network |
PS=WLAN |
PS |
Indicates terminating access is over WLAN |
