AF-Application-Identifier AVP Generation

By default, the Oracle Communications Session Border Controller populates the AF-Application-Identifier AVP with the hostname parameter of the external policy server object that receive's the AAR for the call.

The Oracle Communications Session Border Controller can populate the AF-Application-Identifier AVP with the IMS Communication Service Identifier (ICSI). 3GPP TS 24.173 defines the ICSI format as:

urn:urn-xxx:3gppservice.ims.icsi.mmtel

An ICSI appears in one of the following three SIP headers in an INVITE:

P-Assured-Service
P-Preferred-Service
Accept-Contact

When this feature is configured, the AF-Application-Identifier AVP is inserted into an AAR and sent to the PCRF when the Oracle Communications Session Border Controller (as P-CSCF) receives an INVITE. To configure the feature, navigate to the sip-config configuration element and set the options parameter by typing options, a space, and then +get-icsi-from-sip, as shown in the following example:

ORACLE(sip-config)# options +get-icsi-from-sip

When the Oracle Communications Session Border Controller has an ICSI value from the access UE and the core, it uses the value received from the core. ICSI values received from the network supercede a configured default ICSI value. When the INVITE is received from the access side, ICSI values are taken from the access side until values are received from the core side. If no valid ICSI value is received in a message, and the Oracle Communications Session Border Controller is not configured with a default-icsi value, the external policy server object’s hostname is used for the ICSI value sent to the PCRF. If an INVITE does not contain SDP, no AAR is generated.

AF-Application-Identifier AVP generation occurs for access and core initiated calls.

AVP Generation on Initial INVITE from UE

The Oracle Communications Session Border Controller receives the UE’s INVITE. When configured to send an AAR on receipt of the INVITE, the AF-Application-Identifier AVP is populated with the contents of one of the following headers (in order of precedence) if present:

P-Assured-Service (this header is only expected from trusted UEs)
P-Preferred-Service
Accept-Contact

If none of the above three headers are present, the default value of AF-Application-Identifier shall be used.

If the Oracle Communications Session Border Controller is not configured to send an AAR on receipt of an INVITE, the value from the 3 headers will be cached for later AF-Application-Identifier generation.

AVP Generation on response to Initial INVITE from UE

The Oracle Communications Session Border Controller receives the response (1xx or 200 OK) to the original INVITE. When configured to send an AAR on receipt of the response, the AF-Application-Identifier AVP is populated with the contents of one of the following headers (in order of precedence) if present:

P-Assured-Service
P-Preferred-Service
Accept-Contact header is not expected

Values obtained in this step supercede any value set from the initial INVITE step. If none of the three headers are present, the value determined in the INITIAL invite step is used for the AF-Application-Identifier AVP contents.

AVP generation on reINVITE from UE

The Oracle Communications Session Border Controller can receive a re-INVITEs from the core. The Oracle Communications Session Border Controller populates the AF-Application-Identifier AVP with one of the following headers (in order of precedence) if present:

P-Assured-Service (this header is only expected from trusted UEs)
P-Preferred-Service
Accept-Contact

If none of the three headers are present, the default AF-Application-Identifier value is used.

Responses to the Re-Invites will be treated in the similar manner.

Examples

Example 1:

Received from access UE	Received from core	Sent to PCRF
INVITE with SDP P-A-S, P-P-S, or A-C header contains “P1”	N/A	AAR with AF-A-I AVP contains “P1”
N/A	200 OK with SDP P-A-S, P-P-S, or A-C header contains “P2”	AAR with AF-A-I AVP contains “P2”
re-INVITE with SDP P-A-S, P-P-S, or A-C header contains “P3”	N/A	AAR with AF-A-I AVP contains “P2”
N/A	200 OK with SDP P-A-S, P-P-S, or A-C header contains “P4”	AAR with AF-A-I AVP contains “P4”

Example 2:

Received from access UE	Received from core	Sent to PCRF
INVITE with no SDP	N/A	No AAR generated
N/A	200 OK with SDP P-A-S, P-P-S, or A-C header contains “P2”	AAR with AF-A-I AVP contains “P2”
re-INVITE with SDP P-A-S, P-P-S, or A-C header contains “P3”	N/A	AAR with AF-A-I AVP contains “P2”
N/A	200 OK with SDP P-A-S, P-P-S, or A-C header contains “P4”	AAR with AF-A-I AVP contains “P4”

Example 3:

Received from access UE	Received from core	Sent to PCRF
INVITE with no SDP	N/A	No AAR generated
N/A	200 OK with SDP No P-A-S, P-P-S, or A-C headers	AAR with AF-A-I AVP contains default AF-A-I value.
re-INVITE with SDP P-A-S, P-P-S, or A-C header contains “P3”	N/A	AAR with AF-A-I AVP contains “P3”
N/A	200 OK with SDP P-A-S, P-P-S, or A-C header contains “P4”	AAR with AF-A-I AVP contains “P4”

Example 4:

Received from access UE	Received from core	Sent to PCRF
INVITE with SDP P-A-S, P-P-S, or A-C header contains “P1”	N/A	AAR with AF-A-I AVP contains “P1”
N/A	200 OK with no SDP	AAR with AF-A-I AVP contains “P1”
re-INVITE with SDP P-A-S, P-P-S, or A-C header contains “P3”	N/A	AAR with AF-A-I AVP contains “P1”
N/A	200 OK with SDP P-A-S, P-P-S, or A-C header contains “P4”	AAR with AF-A-I AVP contains “P4”

Example 5:

Received from access UE	Received from core	Sent to PCRF
INVITE with no SDP	N/A	No AAR generated
N/A	183 with SDP No P-A-S, P-P-S, or A-C headers	AAR with AF-A-I AVP contains ext-policy-server’s “hostname”
PRACK with SDP P-A-S, P-P-S, or A-C header contains “P1”	N/A	AAR with AF-A-I AVP contains “P1”
N/A	200 OK with no SDP	No AAR generated
N/A	200 OK (INVITE) with SDP P-A-S, P-P-S, or A-C header contains “P4”	AAR with AF-A-I AVP contains “P4”

Example 6:

Received from access UE	Received from core	Sent to PCRF
INVITE with SDP P-A-S, P-P-S, or A-C header contains “P1”	N/A	AAR with AF-A-I AVP contains “P1”
N/A	200 OK with SDP P-A-S, P-P-S, or A-C header contains “P2”	AAR with AF-A-I AVP contains “P2”
N/A	re-INVITE with SDP P-A-S, P-P-S, or A-C header contains “P3”	AAR with AF-A-I AVP contains “P3”
200 OK with SDP P-A-S, P-P-S, or A-C header contains “P4”	N/A	AAR with AF-A-I AVP contains “P3”

AVP Generation on Initial INVITE from core

The Oracle Communications Session Border Controller receives the original INVITE. When configured to send an AAR on receipt of the INVITE, the AF-Application-Identifier AVP is populated with the contents of one of the following headers (in order of precedence) if present:

P-Assured-Service
P-Preferred-Service
Accept-Contact

If none of the above three headers are present, the default value of AF-Application-Identifier shall be used.

AVP Generation on response to initial INVITE from core

The Oracle Communications Session Border Controller receives the response (1xx or 200 OK) to the original INVITE. When configured to send an AAR on receipt of the response, if none of the three headers (P-Assured-Service, P-Preferred-Service, or Accept-Contact) were present in the original INVITE, the Oracle Communications Session Border Controller populates the AF-Application-Identifier AVP with the contents of one of the following headers (in order of precedence) if present:

P-Assured-Service (this header is only expected from trusted UEs)
P-Preferred-Service
Accept-Contact header is not expected

If none of the three headers are present, the value determined in the INITIAL invite step is used for the AF-Application-Identifier AVP contents.

AVP generation on reINVITE from core

The Oracle Communications Session Border Controller can receive re-INVITEs from the core. The Oracle Communications Session Border Controller populates the AF-Application-Identifier AVP with one of the following headers (in order of precedence) if present:

P-Assured-Service (this header is only expected from trusted UEs)
P-Preferred-Service
Accept-Contact