VoLTE QoS Assessment

High Quality of Service (QoS) is essential to providing a satisfactory user experience. QoS can be an issue in complex end-to-end systems such as IMS running over LTE, where interoperability is a key to the provision of good QoS.

Scope & Technical objectives

The event aimed at validating and evaluating the different methodologies described in ETSI TS 103 189 to assess the quality of speech of VoLTE calls.

TS 103 189 “End-to-end QoS assessment for VoLTE and RCS Interop Events”, is the result of a joint effort of the Technical Committee Core Network and Interoperability Testing (TC INT) and the Technical Committee Speech and multimedia Transmission Quality (TC STQ) to complement the existing Test Suites for IMS and RCS Interoperability (TS 186 011 and TS 102 901) with tests for QoS aspects.

The event was supported by several organisations, including:

  • Com4Innov, who provided the access to a real size LTE / IMS test network deployed in Sophia Antipolis, as well as a number of different User Equipments.
  • HeadAcoustics, who provided the equipment required to run the end to end QoS assessment on both the acoustical and electrical interfaces.
  • AT4Wireless, who provided the test equipment required to perform parallel network performance measures during the end to end QoS assessment sessions.
  • In addition, ETSI Specialist Task Force (STF) 453 provided QoS testing expertise and compiled the findings during the validation sessions that were used as input for a revision of ETSI TS 103 189.


This event allowed to validate over 76% of the test cases in TS 103 189, and covered most of the test cases addressing speech quality. The event was also most helpful to identify gaps and potential improvements in TS 103 189, which include:

  • two new test setups, dealing with electrical-to-acoustic and acoustic-to-electrical configurations
  • the documentation of a procedure for electrical interface level adjustment
  • the documentation of the pertinence of testing in 2 directions in symmetrical configurations (acoustic-to-acoustic and electrical-to-electrical)
  • the need to report on the environmental conditions during the test sessions
  • some clarifications on the network performance parameters to be measured during the test sessions

One of the conclusions of the Plugtests was the submission of a new Work Item to TC INT to address those gaps and improvements in a revised version of TS 103 189.

This event was supported by the European Commission.