# Summary of DECT Liaison Statement on LC3plus 1.25ms Frame Duration Availability

## Document Overview

This is a Liaison Statement from ETSI TC DECT to 3GPP SA4 (S4-260032) responding to a previous 3GPP request (S4-241377) regarding LC3plus integration in 3GPP ISAR. The document announces the availability of a new LC3plus specification version with ultra-low-delay capabilities.

## Main Technical Contributions

### New LC3plus Version Release

ETSI TC DECT announces the publication of **ETSI TS 103 634 V1.6.1** (October 2025), which includes both updated specification text and reference software.

### Ultra-Low-Delay Mode Specifications

The key technical addition is a new **1.25ms frame duration mode** with the following characteristics:

- **Frame duration**: 1.25ms
- **Total algorithmic delay**: 2.5ms
- **Bitrate range**: 128 to 512 kbps per channel
- **Target application**: 3GPP audio services with very tight latency requirements

### Additional Updates in V1.6.1

The revision includes several maintenance and compatibility improvements:

- **Bug fixes and maintenance** for all legacy modes
- **Improved compatibility** of floating-point software with the STL WMC (Weighted Million Operations) complexity estimation tool

## Context and Future Updates

ETSI TC DECT indicates this update directly addresses 3GPP SA4's previous liaison regarding LC3plus integration in ISAR and commits to providing future updates on new revisions of ETSI TS 103 634.