(Continuation of Questions 11/16 and 14/16) Motivation
This Question brings together all the aspects of voice band dial up access
and facsimile transmission.
Dial up access over the GSTN is a ubiquitous method of providing connectivity
for many applications including Internet access, facsimile transmission,
point-of-sale terminals, text telephony, security systems, etc. With the
changing paradigm in network access voice band access has evolved to be included
in IP and next generation networks.
With the emergence of packet based networks and specifically voice over
packet, the GSTN has expanded to include the advantages of these network types.
The need to ensure the best performance transmission of voiceband modems and
facsimile over both circuit and packet switched networks is a necessary
requirement. Packet based networks that are designed for voice require methods
and procedures to allow end-point modems to interoperate with the same
performance as expected from circuit switched networks. In this spirit, the
Question has developed Recommendations V.150.1, V.151, V.152, T.37 and T.38, all
of which support different aspects of the transport of either voiceband modem
signals or facsimile over IP networks.
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.
In summary this Question is responsible for all aspects of voice band modem
and facsimile terminal standardization. This includes the functionality and
performance of the terminals and the transport of the signals they generate
across different network types.
The Question will attempt to work electronically where possible and to make
full use of e-mail and conferencing facilities in an attempt to reduce its
carbon footprint.
Study items
Study items to be considered include, but are not limited to:
- Optimised techniques to support the transmission of voice band modem and
facsimile signals over packet switched networks (IP ones in particular), using
media gateways
- Modulation techniques for high-speed voiceband modems and facsimile connected
to either an analogue local loop or directly to a circuit-switched digital
network. Also to be considered are methods and procedures for initial training,
retraining, rate re-negotiation, optimised modulation and data transmission
performance, fallback to other modulation modes, etc
- Compatibility and interaction with network equipment, such as CME, VED and
echo control devices
- Interworking issues arising from the use of modems on various multimedia
platforms
- Means for evaluating voiceband modem and facsimile terminal performance,
including the specification of network models and test procedures
- DTE-DCE interchange circuits including functional and electrical
characteristics
- Protocols to be used by the DTE to transfer information over the DTE-DCE
interface for the purposes of configuration and control of the local DCE by the
DTE and reliable interworking between DTEs on the GSTN
- DCE to DCE protocols for half-duplex operation, statistical multiplexing,
secure access and privacy of data, compression of synchronous data, improved
data compression algorithms and management of remote DCEs
- Terminal adapters (TAs) for devices having V-series interfaces for use on ISDN
bearer services. This includes their use on multi-use bearer and other bearer
services
- Definition of new or amended capabilities and their implementation for Group 3
and/or Group 4 terminals:
- Definition of service and new usage of facsimile
- Support for new image compression and colour schemes for facsimile
- Develop new and updated test images and documents
- Inter-working between facsimile terminals connected to different networks
types
- The study of methods and procedures for the enhancement of real-time facsimile
transmission over NGN including:
- Revisions to transport layer and call control protocols, operation over mobile
packet networks, Gateway and IAF functionality and secure transmission
- Study of hybrid GSTN/IP tandem networks upon facsimile transmission
- The study of methods and procedures for the enhancement of store and forward
facsimile transmission using Internet mail capabilities
-
Consideration of the effect on the facsimile quality of service of the changes
being made to those networks that support facsimile communication. Examples
include the following list of items:
- Terminal-network interaction
- Improvement of performance on networks with different quality of service
- Maintenance of related Recommendations: F.162, F.163, F.170, F.171, F.182bis,
F.185, F.190, T.4, T.5, T.6, T.22, T.23, T.24, T.30, T.31, T.32, T.33, T.35,
T.36, T.37, T.38, T.39, T.42, T.43, T.44, T.45, T.503, T.563,V.8, V.8bis, V.17,
V.21, V.22, V.22 bis, V.24, V.27, V.27 bis, V.27 ter, V.29, V.32, V.32 bis,
V.34, V.42, V.42 bis, V.43, V.44, V.56 bis, V.56 ter, V.59, V.61, V.70, V.75,
V.76, V.80, V.90, V.91, V.92, V.110, V.120, V.130, V.150.0, V.150.1, V.250,
V.251, V.252, and V.253
- Consider any additions to Recommendations that may help to measure and reduce
the impact of climate change. Examples include reduced power consumption of
hardware and hardware tools, and reduced complexity of algorithms
Tasks
Tasks include, but are not limited to:
- Development of enhancements to Recommendation V.150.x (2005) series
- Develop new Recommendation for the transport of facsimile and modem signals
between two IP networks that use different transport methods
- Coordinate the application and integration of V.150.1, V.151 and V.152 with
other relevant Recommendations
- Development of new DTE-DCE interface-related Recommendations as well as the
revision of existing ones, new control Recommendations as well as the update of
Recommendations V.25X-series and V.80
- Development of new and improved data compression techniques
- Extension of Group 3 and Group 4 facsimile capabilities
- Revision of T.44, T.43, T.4 and T.30 on display oriented colour space
- Enhancement of T.38 on gateway functionality and security aspects
An up-to-date status of work under this Question is found in the SG 16 work
programme (http://itu.int/ITU-T/workprog/wp_search.aspx?isn_sg=554).
Relationships
Recommendations:
- E.451 through E.459, E.460, F.162, F.163, F.170, F.182 bis, F.185, G.711,
G.799.1, G.769, H.225, H.323, H.245, H.248, I.366.2, I.741, T.6, T.22, T.23,
T.24, T.31, T.32, T.33, T.35, T.36, T.39, T.66, T.400 series,T.8x series, T.800
series, X.3, X.38 and X.39
Questions:
- 1, 2 and 3/16 on gateway access to IP networks
- 15, 16 and 18/16 on network signal processing
Study Groups:
- ITU-T SG 2 on services
- ITU-T SG 11 on network signalling systems
- ITU-T SG 12 on speech performance, QoS and QoE
- ITU-T SG 13 on ISDN, voiceband and text telephone modems over AAL2
- ITU-T SG 15 on access network issues
- ITU-T SG 17 on DTE-DCE interface issues
Other Bodies:
- ISO/IEC JTC 1/SC 6 on DTE-DCE interface issues HDLC and data compression
- Other organizations using "AT" commands, e.g. ETSI, 3GPP, 3GPP2, TIA
- ISO/IEC, IETF, ETSI, TIA, CIE, ICC for facsimile and audio conferencing
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