QUESTION 21/15 - Transport Network Equipment for Interconnecting GSTN and IP Networks

Type of Question

Task oriented leading to a new Recommendation or Recommendations.

 Background and Justification

Voice and voice-band traffic in international networks has traditionally been transported by circuit switched systems and equipment. With the advent of the IP-based networks, and as a result of its considerable growth and pervasive nature, more and more speech traffic is expected to be carried over transport networks optimized for IP traffic.

There is recognition that IP-based transport of speech signals is a rapidly growing area of network development. For the next several years, much of this voice transport related to IP will pass through equipment interconnecting GSTN and IP networks. GSTN in the context of this Question is the General Switched Telephone Network and refers to PSTN, N-ISDN, B-ISDN, and mobile networks. IP in the context of this Question is the Internet Protocol and IP networks in this context are networks optimized for the transport of IP.

Given that voice and voice-band services remain a significant part of telecommunications, there is a need to ensure a high quality of service for speech carried in part or wholly via Internet Protocol. Recommendations for protocols exist or are being developed for converting and transporting GSTN originated voice and voice-band data over IP networks. The interworking of these is covered by other Recommendations. It is not the purpose of this Question to redefine these existing protocols or define new ones, but rather to have them encompassed under one equipment specification to ensure that the correct and appropriate functionality is present in this equipment .

Question

What functionality, interfaces, and functional tests need to be specified and recommended for Transport network equipment for Interconnecting GSTN and IP Networks (TIGIN) to provide good performance in the network? What impact do speech-processing issues related to this TIGIN equipment have on overall network performance.

 Study items

  1. What overall functionality should TIGIN possess?
    Amongst other issues, this item will identify relevant voice coding, interface, signalling, call control, and interworking Recommendations that have been developed elsewhere within the ITU-T in the context of their operation within TIGIN.
  2. What interfaces within GSTN and IP interface points should TIGIN possess?
    Both physical and logical interfaces will be identified under this item. Relevant Recommendations will be referenced where applicable.
  3. What protocols and Internet interworking functions are to be supported by TIGIN ?
    This item will identify inband speech coding, inband signalling and voice-band data protocols supported on the GSTN interface, as well as IP packet protocols that are used to interface to the IP interface.
  4. What control and operation interfaces need to be specified?
    This item will identify which Recommendations need to be supported within the equipment for control, configuration, and management.
  5. What should be recommended for TIGIN in the areas of level offset, echo return loss and background noise?
    Work here will identify and recommend specific requirements for speech, inband signalling and voiceband signals passing through TIGIN.
  6. What should be recommended in TIGIN functionality to ensure minimal end-to-end delay?
    It is recognized that IP networks will often cause a longer end-to-end delay than traditional circuit switched networks. This item will investigate the impact of these delays on Signal Processing Network Equipment (SPNE) and define appropriate requirements.
  7. What are the effects of placing TIGINs in tandem and what should be recommended to minimize the impact of these effects?
    Similar tests will be proposed to those currently being considered within the Questions in Study Group 15 dealing with echo control and automatic level control equipment.
  8. What degradation is there when low bit rate coders and other non-linearities are present in connections incorporating TIGIN, and what should be recommended to minimize the impact of these degradations ?
    This item will study the impact of speech degradation on other SPNE (e.g. DCEM, EC) caused by non-linearities present within the IP network.
  9. What tests should be included to guarantee acceptable behavior with voiceband data signals, signalling tones, call-processing tones, speech, etc.?
    Previous work done this area for echo canceller equipment and DCMEs will be taken into account.
  10. What hardware and software tools are needed to support testing of TIGIN ?
  11. What is the impact of evolving terminal equipment such as modems, fax, wireless and multimedia terminals on TIGIN ?
    Reference will be made to any ongoing work in other Study Groups as it pertains to TIGIN equipment requirements.

Specific tasks

Relationships