B.2 Methodology

29.1653GPPInter-IMS Network to Network Interface (NNI)Release 18TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

The meaning of the notation codes used in the tables in subsequent clauses is as follows:

In the "RFC status" column, the notation codes defined in IETF RFC 3261 [13] clause 20 are applied.

In the "II-NNI condition" column the notation codes defined in table B.2.1 are used. If a capability of a SIP header field is specified as either optional or conditional in table 6.1.3.1, then "II-NNI condition" of the SIP header field is described with conditional expression.

In each request-related table, the order of SIP header fields inherits that of clause A.2.2 of 3GPP TS 24.229 [5].

In each response-related table, the SIP status code for which the header field is applicable is described in the "SIP status code" column. The notation codes for the "where" column as defined in IETF RFC 3261 [13] clause 20 are applied. The notation code "r" in "SIP status code" column corresponds to any SIP status code which is described in annex A of 3GPP TS 24.229 [5] for the corresponding method. Any SIP header field not listed in a table is not applicable for the corresponding SIP message.

Table B.2.1: Key to notation codes for SIP header fields in dynamic view for II-NNI

Notation code (NOTE 1)	Meaning
dc	The SIP header field is required to be present in a SIP message over II-NNI according to the procedures specified in other specifications e.g. 3GPP TS 24.229 [5].
dm	The SIP header field shall be always present in a SIP message over II-NNI, and if received, it must be handled according to 3GPP TS 24.229 [5].
dm*	The SIP header field should be present in a SIP message over II-NNI, but the IMS network need to be prepared to receive a SIP message without that header field.
do	The SIP header field can be present in a SIP message over II-NNI, and if received, it must be handled according to 3GPP TS 24.229 [5]. (NOTE 2)
dt	The header field should be present in a SIP message over II-NNI, but the IMS network need to be prepared to receive a SIP message without that header field. If TCP is used as a transport, then the header field must be present in a SIP message.
d*	The SIP header field is required to be present in a SIP message if the message body is not empty.
dn/a	The SIP header field is shall not be present in a SIP message over II-NNI. (NOTE 3)
dc<integer>	The condition for the presence of the SIP header field. <integer> is the identifier of the condition. This notation code is applied only in each request-related or response-related table.
NOTE 1: The meaning of the notation codes is same as in IETF RFC 3261 [13] clause 20 and "d" is used to emphasise the dynamic view. NOTE 2: If specified by local policy rules, the IBCF acting as entry point may omit or modify any received SIP header fields prior to forwarding SIP messages as specified in 3GPP TS 24.229 [5] clause 5.10.6.2. NOTE 3: The SIP header field can be removed at the IBCF acting as exit point by using screening functionality defined in 3GPP TS 24.229 [5] clause 5.10.6.2.