(Continuation of Q.4/16, Q.10/16 and Q.23/16)

Type of Question

Task-oriented Question designed to lead to one or more Recommendations.

Background

During the 1997-2000 study period, activity related to voiceband modems has been high, particularly within Questions 4/16 and 23/16. Of particular interest is network access, which has become by far the dominant application for voiceband modems. Today, most people use modems to access the Internet, an online service or a corporate network. In an increasing number of such applications, the network connection consists of a central-site modem directly connected to the digital backbone of the PSTN and a remote user's modem connected via an analogue local loop to the PSTN.

Although digital networks are rapidly being deployed around the world, analogue access will remain the only choice in many locations. Users in these locations will continue to have the need to access and exchange electronic information. Therefore, the continued study of modem technology is required to supply these users with the best standardized tools to meet their needs.

Items for study

1) Development of modulation techniques for high-speed voiceband modems connected to either an analogue local loop or directly to the digital network.

2) Development of modulation techniques compatible with an optional linear coding mode in the network.

3) Development of procedures for initial training, retraining, rate re-negotiation (including seamless), determination of a given connection's ability to support a particular modulation mode, fallback to other modulation modes, etc.

4) Development of procedures for the exchange of capabilities and selection of operating mode, such as enhancements to Recommendation V.8 and V.8bis, as well as procedures for switching between operating modes.

5) Development of techniques to support the transmission of data over IP networks, such as signal discrimination techniques for IP gateways.

6) Compatibility with network equipment, such as DCME/PCME and echo control devices.

7) Interworking issues arising from the use of modems on various multimedia platforms.

8) Definition of means for evaluating voiceband modem performance, including the specification of network models and test procedures.

9) Maintenance of existing modem and related Recommendation (where appropriate work may be delegated to Questions 12 or 13/16).

Specific task objectives

• Development of enhancements to Recommendation V.90 (1998).
• Development of enhancements to Recommendations V.8 and V.8bis.
• Development of a network model and test procedures for the evaluation of V.9x-series modem performance.

Relationships

• Recommendations V.91, V.90, V.34, V.8, V.8bis, V.56bis, V.56ter and G.711.
• Question 13/16 on DTE-DCE interface and protocol issues.
• Question 12/16 on DCE-DCE protocols for the PSTN and ISDN.
• Question 2/16 and 3/16 on gateway access to IP networks.
• ITU-T Study Group 8 on facsimile requirements for V.9x-series modems.
• ITU-T Study Group 15 on PSTN characteristics.