K.2 Definition of VoIP LI Correlation header

33.1083G Security3GPPHandover interface for Lawful Interception (LI)Release 17TS

The VoipLIC-header is defined in ASN.1 [5] (see annex B.12) and is encoded according to BER [6]. It contains the following attributes:

– Object Identifier (hi3voipDomainId)

– Lawful Interception Identifier (lIID, optional). The handling of Lawful Interception Identifier is done according to national requirements.

– VoIP Correlation Number (voipCorrelationNumber). The handling of VoIP Correlation Number is to be done according to clause 12.1.4.

– Time Stamp (timeStamp, optional). The handling of time-stamp is done according to national requirements.

Editor’s Note: The time-stamp may have to be made mandatory for VoIP CC. It is for further study.

– Sequence Number (sequence-number). Sequence Number is an integer incremented each time a T-PDU is delivered. Handling of sequence number is done according to national requirements.

Editor’s Note: The need for sending the sequence-number with TCP as the transport protocol is for further study.

– TPDU direction (t-PDU-direction) indicates the direction of the T-PDU and has the following values:

– From the Target. (from-target). The VoIP-CC-PDU is coming from the target.

– To the Target (to-target). The VoIP-CC-PDU is sent to the target.

– Combined (combined). The VoIP-CC-PDU includes both from the target and to the target.

– Not Known (unknown). The direction of VoIP-CC-PDU cannot be determined.

– National parameters (national-HI3-ASN1Parameters, optional). This parameter is encoded according to national requirements.

– ICE type (ice-type, optional). This indicates in which node the T-PDU was intercepted. This parameter is provided if available at the Delivery Function/Mediation Function. The following are the possible ICE Type values:

– GGSN (ggsn). The VoIP CC was intercepted at the GGSN.

– PDN Gateway (pDN-GW). The VoIP CC was intercepted at the PDN-GW.

– IMS AGW (aGW). The VoIP CC was intercepted at the IMS AGW.

– Transit Gateway (trGW). The VoIP CC was intercepted at the TrGW.

– IM-MGW (mGW). The VoIP CC was intercepted at the IM-MGW.

– MRF (mRF). The VoIP CC was intercepted at the MRF.

– Other nodes (other). The VoIP CC was intercepted at a media node not mentioned above.

– Not known (unknown). The media that intercepts the VoIP CC is not known.

– Payload Description (payload-description, optional):

As an optional implementation this parameter describes the content of the Payload parameter in order to ease the LEMF to process the HI3 autonomously (meaning without waiting for media info from HI2).