7.6 3GPP IM CN subsystem XML body

24.2293GPPIP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP)Release 18Stage 3TS

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

7.6.1 General

This subclause contains the 3GPP IM CN Subsystem XML body in XML format. The 3GPP IM CN Subsystem XML shall be valid against the 3GPP IM CN Subsystem XML schema defined in table 7.6.1.

Any SIP User Agent or proxy may insert or remove the 3GPP IM CN subsystem XML body or parts of it, as required, in any SIP message. The 3GPP IM CN subsystem XML body shall not be forwarded outside a 3GPP network.

See subclause 7.6.4 and subclause 7.6.5 for the associated MIME type definition.

7.6.2 Document Type Definition

The XML Schema, is defined in table 7.6.1.

Table 7.6.1: IM CN subsystem XML body, XML Schema

<?xml version="1.0" encoding="UTF-8"?>

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified" version="1">

<xs:complexType name="tIMS3GPP">

<xs:sequence>

<xs:choice>

<xs:element name="alternative-service" type="tAlternativeService"/>

<xs:element name="service-info" type="xs:string"/>

</xs:choice>

<xs:any namespace="##any" processContents="lax" minOccurs="0" maxOccurs="unbounded"/>

</xs:sequence>

<xs:attribute name="version" type="xs:decimal" use="required"/>

<xs:anyAttribute/>

</xs:complexType>

<xs:complexType name="tAlternativeService">

<xs:sequence>

<xs:element ref="type"/>

<xs:element name="reason" type="xs:string"/>

<xs:any namespace="##any" processContents="lax" minOccurs="0" maxOccurs="unbounded"/>

</xs:sequence>

<xs:anyAttribute/>

</xs:complexType>

<!– root element –>

<xs:element name="ims-3gpp" type="tIMS3GPP"/>

<xs:element name="type" type="xs:string"/>

<!– action element for //ims-3gpp//alternative-service –>

<xs:element name="action" type="xs:string"/>

</xs:schema>

7.6.3 XML Schema description

This subclause describes the elements of the IM CN subsystem XML Schema as defined in table 7.6.1.

<ims-3gpp>: The <ims-3gpp> element is the root element of the IM CN subsystem XML body. It is always present. XML instance documents of future versions of the XML Schema in table 7.6.1 is valid against the XML Schema in table 7.6.1 in this document. XML instance documents of the XML Schema in table 7.6.1 in the present document have a version attribute value, part of the <ims-3gpp> element, that is equal to the value of the XML Schema version described in the present document.

<service-info>: the transparent element received from the HSS for a particular trigger point are placed within this optional element.

<alternative-service>: in the present document, the alternative service is used as a response for an attempt to establish an emergency session within the IM CN subsystem or as a response to initiate S-CSCF restoration procedures. The element describes an alternative service where the call should success. The alternative service is described by the type of service information. A possible reason cause why an alternative service is suggested may be included.

In the present document, the <alternative-service> element contains a <type> element, a <reason> element, and an optional <action> element.

The <type> element indicates the type of alternative service. The <type> element contains only the values specified in table 7.6.2 in the present document.

Table 7.6.2: ABNF syntax of values of the <type> element

emergency-value = %x65.6D.65.72.67.65.6E.63.79 ; "emergency"

restoration-value = %x72.65.73.74.6F.72.61.74.69.6F.6E ; "restoration"

The <action> element contains only the values specified in table 7.6.3 in the present document.

Table 7.6.3: ABNF syntax of values of the <action> element

emergency-registration-value = %x65.6D.65.72.67.65.6E.63.79.2D.72.65.67.69.73.74.72.61.74.69.6F.6E ; "emergency-registration"

initial-registration-value = %x69.6E.69.74.69.61.6C.2D.72.65.67.69.73.74.72.61.74.69.6F.6E ; "initial-registration"

anonymous-emergencycall-value = %x61.6E.6F.6E.79.6D.6F.75.73.2D.65.6D.65.72.67.65.6E.63.79.63.61.6C.6C ; "anonymous-emergencycall"

The <reason> element contains an explanatory text with the reason why the session setup has been redirected. A UE may use this information to give an indication to the user.

If included in the IM CN subsystem XML body:

1. the <type> element with the value "emergency" is included as the first child element of the <alternative-service> element;

2. the <type> element with the value "restoration" is included as one of the following:

a) the first child element of the <alternative-service> element; or

b) the third or later child element of the <alternative-service> element;

3. the <action> element with the value "emergency-registration" is includes as the third child element of the <alternative-service> element;

4. the <action> element with value "initial-registration" is included as the third or later child element of the <alternative-service> element; and

5. the <action> element with value "anonymous-emergencycall" is included as the third or later child element of the <alternative-service> element.

NOTE: When included, the <action> and the second occurence of the <type> elements are validated by the <xs:any namespace="##any" processContents="lax" minOccurs="0" maxOccurs="unbounded"/> particle of their parent elements.

7.6.4 MIME type definition

7.6.4.1 Introduction

This subclause defines the MIME type for "application/3gpp-ims+xml". A 3GPP IM CN subsystem XML Document can be identified with this media type.

7.6.4.2 Syntax

The following optional parameters are defined:

– "charset": the parameter has identical semantics to the charset parameter of the "application/xml" media type as specified in RFC 3023 [132].

– "sv" or "schemaversion": the syntax for the "sv" or "schemaversion" parameter is specified in table 7.6.4:

Table 7.6.4: Syntax of the "sv" or "schemaversion" parameter

m-parameter =/ ("sv" / "schemaversion") EQUAL LDQUOT [ sv-value-list ] RDQUOT

sv-value-list = sv-value-range *( "," sv-value )

sv-value-range = sv-value [ "-" sv-value ]

sv-value = number / token

number = 1*DIGIT [ "." 1*DIGIT ]

The BNF for m-parameter is taken from RFC 3261 [26] and modified accordingly.

7.6.4.3 Operation

The encoding considerations for "application/3gpp-ims+xml" are identical to those of "application/xml" as described in RFC 3023 [132].

The "sv" or "schemaversion" parameter’s value is used to indicate:

– the versions of the 3GPP IM CN Subsystem XML schema that can be used to validate the 3GPP IM CN subsystem XML body (if the MIME type and parameter are present in the Content-Type header field); or

– the accepted versions of the 3GPP IM CN Subsystem XML body (if the MIME type and parameter are present in the Accept header field).

If the "sv" and "schemaversion" parameter are absent, it shall be assumed that version 1 of the XML Schema for the IM CN subsystem XML body is supported.

7.6.5 IANA Registration

NOTE: RFC 4288 [161], subclause 9, states the process that applies in case of changes to the registry of media types. Any future changes to the format or to subclause 7.6.5 would invoke this procedure.

MIME media type name:

application

MIME subtype name:

3gpp-ims+xml

Required parameters:

None

Optional parameters:

"charset" the parameter has identical semantics to the charset parameter of the "application/xml" media type as specified in RFC 3023 [132].

"sv" or "schemaversion" the parameter’s value is used to indicate:

– the versions of the 3GPP IP Multimedia (IM) Core Network (CN) subsystem XML schema that can be used to validate the 3GPP IM CN subsystem XML body (if the MIME type and parameter are present in the Content-Type header field); or

– the accepted versions of the 3GPP IM CN Subsystem XML body (if the MIME type and parameter are present in the Accept header field).

If the "sv" and "schemaversion" parameter are absent, it shall be assumed that version 1 of the XML Schema for the IM CN subsystem XML body is supported.

Encoding considerations:

Same as encoding considerations of application/xml as specified in RFC 3023 [132]

Security considerations:

Same as general security considerations for application/xml as specified in subclause 10 of RFC 3023 [132].

In addition, this content type provides a format for exchanging information in SIP, so the security considerations from RFC 3261 [26] apply.

Interoperability considerations:

Same as Interoperability considerations as specified in subclause 3.1 of RFC 3023 [132].

If both "sv" and "schemaversion" are specified, then the value of "schemaversion" is ignored

Published specification:

3GPP TS 24.229: "IP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP), stage 3", as published in subclause 7.6.5, version 8.9.0.

Available via <http://www.3gpp.org/specs/numbering.htm>.

Applications which use this media:

Applications that use the 3GPP IM CN Subsystem as defined by 3GPP.

Intended usage:

COMMON

Additional information:

1. Magic number(s): none

2. File extension(s): none

3. Macintosh file type code: none

4. Object Identifiers: none