The entire clause 11 is a national option and is subject to national regulations. The covered cases are where the conference services are in the domain of the intercepting operator. The following cases are covered.
A target's conference call is the target. This may be where the target is the head of the conference. IRI and CC for this conference is reported. The following are examples of information that is reported.
For example, the starting and ending of a conference as well as any parties joined or removed from the conference call are reported.
Reporting of CC for held conferences initiated by the target.
A conference that itself is directly the target of interception. This case is applicable only provided that the conference is identified by a proper identity for LI in IMS domain (Conference URI or Conference Factory URI). The IRI and CC for this conference is reported.
For example, the starting and ending or a conference as well as any parties joined or removed from the conference call are reported.
The case when an target joins an associate's conference is for further study.
The key elements for interception of conference services are the AS/MRFC and MRFP. IRI associated with the conference services that are to be intercepted is reported by the AS/MRFC while the CC associated with the conference service is reported by the MRFP.
National regulations on a per interception basis may limit delivery of communications (CC and IRI) of an outbound international roaming target by the HPLMN as described in clause 5.1.4 of TS 33.106.
If roaming interception is not allowed and it is determined that the target is outside the country, the HPLMN shall act as follows:
The HPLMN shall not report IRI and CC for the target's conferencing services while the target is in the VPLMN and is connected to the HPLMN conferencing service.
Non-communications-associated IRI (e.g. those identified by the HSS) are not affected by this requirement.
Interception (as defined in 11.1) for IMS Conference Services is started when the first of any one of the following occurs:
When a target requests that a conference be created
When a target successfully provisions a conference
When a target provisioned or requested conference is started (i.e., the first party is joined to the conference)
When a conference that is a target of interception is started (i.e., the first party is joined to the conference)
When interception is activated (on a conference or a conference owner) during an ongoing conference
When parties have joined a conference and communication is started or enabled by the conference server in cases where the conference is a target of interception or when it is a target's conference.
If the target of interception has provisioned or requested a conference to be created, interception on IMS Conference Services shall begin regardless whether the target of interception has joined the conference. Interception of IMS Conference Services shall continue if the target of interception is on hold and the conference continues.
The access method for the delivery of IMS conference services intercept content of communication (CC) is based on duplication of packets without modification at the MRFP for conferences that are to be intercepted. The duplicated packets with additional information in the header, as described in the following sections, are sent to DF3 for further delivery. For a target's conference call held by the target, the MRFP duplicates the CC for conference call held by the target, in accordance with national regulations. For a conference call that is the target of interception, the MRFP duplicates the CC for the conference.
There is an issue of combined versus separated delivery. With combined delivery, one method for intercepting the CC would be to create a virtual conference port (not visible to others) through which a copy of the combined CC is passed over the X3 interface (Y conferees means 1 content stream). With the separated delivery approach, each conferee's connection to the conference shall be intercepted and passed over the X3 interface (Y conferees, means Y pairs of bi-directional content streams).
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Figure 11.1: Configuration for interception of IMS Conference Services CC
In addition to the intercepted content of communications, the following information may need to be transferred from the MRFP to the DF3 in order to allow the DF3 to perform its functionality:
identity used for interception;
Information passed between the MRFC and MRFP for correlation shall uniquely identify the mixing of associated media streams for a conference distinct from any other mixing or media handling. An example is how H.248 uses a context identifier to do this.
the identity of source (i.e., conference party identity) of a media stream;
time stamp - optional;
direction (incoming or outgoing stream) - optional.
A Party Leave-event is generated in the following cases:
When a party leaves a target's conference or a conference that is the target of interception. This includes situations where the party simply disconnects themselves from the conference (hang up), the party's connection to the conference is broken (e.g., party leaves wireless coverage area), and where the party's connection to the conference is forcefully terminated due to another party's drop request or operator policy.
When a party unsuccessfully attempts to drop another party from the conference. This applies to all the conferencing scenarios described earlier.
The fields, shown in Table 11.3.4, will be delivered to the DF2, if available, by the AS/MRFC.
When a conference is created, a Creation of Conference-event is generated in the following cases:
When a target successfully provisions or requests a conference to be created.
This event is applicable provided that at least one of the two identities (IMPU, IMPI) are available at the AS/MRFC. Other scenarios, such as in case the creation is done via a web interface and the IMPU/IMPI cannot be seen are outside the scope of this specification.
The fields, shown in Table 11.3.7, will be delivered to the DF2, if available, by the AS/MRFC.
When a conference is updated, an Update of Conference-event is generated in the following cases:
When a target successfully provisions or requests a conference to be updated (e.g., changes to List of Potential Conferees, Start Time, End Time, Recurrence Information, or Cancellation of Conference).
This event is applicable provided that at least one of the two identities (IMPU, IMPI) are available at the AS/MRFC. Other scenarios, such as in case the update is done via a web interface and the IMPU/IMPI cannot be seen are outside the scope of this specification.
The fields, shown in Table 11.3.8, will be delivered to the DF2, if available, by the AS/MRFC.