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Question 3/12

Question 3/12 – Speech transmission characteristics of communication terminals for fixed circuit-switched, mobile and packet-switched (IP) networks
(Continuation of Question 3/12)


With the wide use and fast evolution of communication terminals, the work defined in this Question remains an important area for international telecommunication standardization. On the one hand, there are numerous handsets, headsets and hands-free terminals in market or under design. On the other hand, progress in signal processing and microchip technology encourage the application of speech enhancement techniques in terminal design. How to evaluate these new terminals effectively is still a challenge and should be considered adequately in the future. Furthermore, some new test signals, such as real speech signals, are deemed to bring about huge changes on application of terminal measurement methods.

Considering the needs for super-wideband and full-band application, this Question should research the transmission characteristics of super-wideband and full-band terminals and relevant application of measurement methodology. Unlike traditional speech terminals, terminals directly interfacing with packet-switched networks (VoIP) should consider other IP-related parameters.

Speech characteristics and objective measurement methods for multimedia terminals, for example, videotel, audio-visual terminal, teleconference, videoconference and telemeeting equipment, also require further research and development.
The following Recommendations/Supplements, in force at the time of approval of this Question, fall under its responsibility:
P.300, P.310, P.311, P.313, P.341, P.342, P.350, P.370, P Suppl. 10, P Suppl. 16.


Study items to be considered include, but are not limited to:

  •  What enhancement or new Recommendation needs to be developed to define headset and handsfree transmission characteristics for mobile and cordless terminals?
  • What enhancements to existing Recommendations are needed to specify the performances of noise reduction and other acoustic enhancement devices within terminals? 
  •  What enhancements to existing Recommendations are needed to specify the performance of mixed operation between Narrow band and other wider band terminals in teleconferencing situations? 
  •  What transmission characteristics and measurement methods are needed for cordless and mobile terminals using Multi Rate Codecs in Narrow band and other wider band applications?
  • What speech transmission characteristics are needed for multimedia terminals?
  •   What kind of simple alignment methodology is needed for VoIP softphone using different coders? 
  •  What new test methods and signals, such as ones defined in P.501 and P.502, are appropriate for testing transmission characteristics of terminal equipment? 
  •  How to use the test signals newly developed in P.501 and measurement methods developed in P.502 to enhance existing Recommendations?
  •  What speech transmission characteristics are particularly needed for VoIP terminals?
  • What are the characteristics and the test methods for terminals implementing Super Wide-Band and full band? 
  •  How can VoIP terminals be tested, considering the assessment methods developed for VoIP gateways in P.1010?
  • What speech transmission characteristics and measurement methods are needed for terminals using new access techniques (e.g. power line access, WLAN, etc.)? 
  •  What other changes and/or improvements can be done for the existing Recommendations (P.300, P.310, P.311, P.313, P.340, P.341, P.342, P.350, P.370)?


The main task of this Question in next study period shall focus on the following:

  • Contribution to enhancement of ITU-T Recommendation G.172.
  • Contribution to enhancement of ITU-T Recommendation P.311 and P.341 or possibly new recommendation on super wideband and full band terminals.

And the following tasks shall also be considered:

  • Contribution to the enhancement of ITU-T Recommendation P.1010.
  • Revision of ITU-T Recommendation P.313 to include speech transmission characteristics for wideband mobile and cordless terminals.
  • Contributions to the existing Recommendation P.501 and P.502.
  • Contribution to enhancement of ITU-T Recommendations P.310, P.342 and G.136.
  • Considering on how to help measure and mitigate climate change.
An up-to-date status of work under this Question is contained in the e SG 12 work programme



  •   P.330, P.340, P.501, P.502, P.1010, G.131, P.1100, P.1110, P.58, P.581
  •   4/12, 5/12, 6/12, 10/12
Study Groups
  •  ITU-T SG 15, SG 16
Standardization bodies