S4-260029 - AI Summary

LS on LI requirements on IMS Data Channel

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LS on LI Requirements on IMS Data Channel

Document Information

  • Meeting: SA3-LI#97 (29 April – 02 May 2025, Washington DC)
  • Document Number: S3i250185
  • Release: Rel-19
  • Work Item: LI19
  • Source: SA3-LI
  • To: SA4, SA2
  • Cc: CT1, SA3

Overall Description

Problem Statement

SA3-LI has identified critical gaps in the current IMS Data Channel encryption architecture that prevent CSPs from meeting lawful interception (LI) requirements specified in TS 33.126, particularly requirements R6.4-160, R6.4-170, R6.4-180, and R6.4-190, including mid-session interception scenarios.

Key Issues Identified

1. Encryption Architecture Limitations

The current encryption and architecture design for IMS Data Channel fails to meet LI requirements in the following scenarios:

  • Roaming cases with S8HR/N9HR model
  • Interoperability cases between two CSPs
  • Direct communications between two users (when at least one is an LI target)

2. LI Access Requirements Not Met

SA3-LI specifies two acceptable approaches for LI:

  1. Preferred: Access to a copy of communication content without confidentiality protection
  2. Required (if preferred not feasible): Access to encryption parameters that enable decryption of encrypted content

Neither approach is currently achievable with the existing IMS Data Channel implementation.

3. Interoperability Gap

When two CSPs interoperate where:
- One CSP uses IMS Data Channel
- The other CSP uses IMS without IMS Data Channel feature
- The LI target is on the CSP without Data Channel

The CSP cannot intercept and provide the content exchanged between the two users, creating a compliance gap.

Reference Architecture

The document references Figure 6.2.10.1-1 from TS 26.114 showing the Data Channel Workflow, indicating the architectural context of the identified issues.

Impact

These limitations create major complications for CSPs to respect their national regulations regarding lawful interception obligations.

Action Requested

SA3-LI requests SA4 and SA2 to:

Develop a solution and architecture for secured IMS Data Channel that enables CSPs to meet the LI requirements as described in TS 33.126.

Next SA3-LI Meetings

  • SA3LI Meeting #98: 15th – 18th July 2025, Florence, Italy
  • SA3LI Meeting #99: 4th – 7th November 2025, TBD, USA
Document Information
TDoc:
S4-260029
Source:
SA3-LI
Type:
LS in
For:
Action
Original Document:
View on 3GPP
Title: LS on LI requirements on IMS Data Channel
Agenda item: 5.2
Agenda item description: Other 3GPP groups
Doc type: LS in
For action: Action
Release: Rel-19
Original LS: s3i250185
Cc: CT1, SA3
To: SA4, SA2
Contact: Andrijana Brekalo
Uploaded: 2026-01-21T15:41:08.240000
Contact ID: 91743
TDoc Status: noted
Reservation date: 21/01/2026 15:37:03
Agenda item sort order: 7