D.1 General

33.1273GPPLawful Interception (LI) architecture and functionsRelease 18TS

The following sub-clauses provide additional details for LI for RCS. Unless specified, the details provided in clause 7.13 apply to all of the following sub-clauses. In general, the specific architecture is used as an example, the location of the POIs may need to be adjusted based on implementation.

The current document defines LI for the following RCS services at the RCS Servers:

– Capability discovery: This service enhances service usability by allowing a user to understand the subset of RCS services available to access and/or communicate with the user’s contacts, at certain points in time.

– Pager mode standalone messaging: This service allows delivering one standalone message which does not exceed 1300 bytes in size to one or several recipients. No SIP session is established to deliver that message. The message is carried in a SIP MESSAGE request.

– Large message mode standalone messaging: This service allows `delivering one standalone message which is larger than 1300 bytes in size to one or more recipients. A SIP session is established for the delivery of one message only. The message is carried on the user plane.

– 1-to-1 chat: This service allows establishing a SIP session between two participants. This session is used to exchange user plane messages. Unlike large message mode standalone messaging, there is no limit to the number of messages being exchanged.

– Group chat: This service allows establishing a SIP session between several participants. This session is used to exchange user plane messages.

– File URL transfer: Delivery of the URL of a file being uploaded to the HTTP Content Server. The delivery of the URL of the file is performed either by pager mode standalone messaging, large message mode standalone messaging, 1-to-1 chat or group chat.

The current document defines LI for the following RCS services at the HTTP Content Servers:

– File upload. A target UE uploads a file to the HTTP Content Server. If the upload procedure is successful, the target UE is provided with a file transfer message body containing file metadata including the file download URL by the HTTP Content Server.

– File download. A target UE downloads a file or any UE downloads a file uploaded by a target from the HTTP Content Server using a download URL. The URL may have been received via one of the RCS messaging services.