The next generation of text telephony in the Nordic countries and Europe is under
development. The next generation of text telephony means telephony that is
Internet (IP) based, and also various mobile terminals. The objective is to clarify the
Nordic standpoints, in order to in this way contribute to increased harmonisation
within the area.
The Nordic standpoints concerning traditional text telephony and text
telephony for everybody
Mobility
Text telephony should be opera t o r- n e u t ral and independent of terminal
manufacturer. Mobile text calls should function in 3G, GSM and future terminals.
The terminals that are also in common use now should also be able to cope with
mobile text, i.e. ‘smartphones’ should not be a basic requirement. A smartphone
combines the functionality of a mobile telephone and a laptop computer in one
and the same terminal. It is desirable that terminal manufacturers facilitate the use
of both voice and text channels simultaneously during a call.
1 The Nordic Forum for Telecommunication and Disability (NFTH) is a collaborative body established in 1987 by The Nordic Cooperation on Disability (NSH) under the Nordic Council of Ministers. NFTH is financed by The Nordic Development Centre for Rehabilitation Technology (NUH), which is a subsidiary of the NSH. The purpose of NFTH is to discuss relevant topics in the field of telecommunications that concern disabled persons and to support the Nordic countries’ endeavours to integrate disabled persons into the information society. NFTH does this by making recommendations and guidelines dealing with the current and future problems of the new information society.
http://www.nuh.fi/NFTH_eng.htm
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Internet
Text telephony should be possible through downloaded software or via the
Internet, on computers with the most common operative systems (Windows,
Macintosh, Linux, etc.). Text telephony should be possible from various computers
with Internet access, including Internet cafés. Between computers, it should be
possible to speak and hear simultaneously as text is being used.
Service interoperability
Within the Nordic countries text telephony between computers, common kinds of
mobile terminals and the analogue text telephones that are used within the Nordic
countries, including Speak directly-functionality, should function. Text telephony
should, if possible, also offer interoperability with common ‘Instant Messaging’
(IM) services, such as MSN Messenger and Yahoo, among others.
Service interoperability can be achieved in various ways. It may, for example, relate
to a central ‘gateway’ solution, or the production of a common technical solution.
It should be possible for text telephony to be used through the various networks
that are common and available in various contexts.
Continuous transmission of text
During a text call it should be possible to transmit continuously so that the
conversation is fluent. A text call should be perceived as occurring in real time and
correspond with a voice conversation, where it is possible to interrupt each other
at any time.
When text is sent at approximately one second intervals, the party conversing
senses the fluency mentioned above. Sending text as blocks (‘chat’) is a
supplement, but it does not completely satisfy the need for a text conversation
corresponding to a conversation that speaking persons experience.
Interoperability for text telephony across IP
With analogue text telephony, s e v e ral different standards have emerged.
Interoperability for text telephony via IP should apply within the EU area, and
preferably globally. The ongoing work to achieve interoperability for text telephony
over IP is of great importance.
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Relay services for text telephony
Relay services facilitate calls between persons with hearing, persons who have
speech impairment, deaf persons and deaf-blind persons. These are crucial services
that assist in creating communication between persons with disability and persons
with hearing. Relay services may be either manual or automatic.
It should be possible to connect relay services the easiest way possible. It is
appropriate that the person calling up should not need to know that, for example,
a certain telephone number leads to a hearing or a deaf person and that the call
is automatically diverted via a relay service when this is necessary.
It is also important that relay services for text telephony and relay services for video
telephony use voice/audio and text in the same way, so that interoperability is
achieved to the highest possible degree between text telephones, video telephones
and total conversation units.
References
NFTH, (2005). The recommendations of the Nordic countries regarding
functionality for text telephony. http://www.nuh.fi/NFTH_2-2005.doc
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2.4.2 Mobile and IP–based text telephony
Flexible text communication services in Sweden
Robert Hecht
Rationale
It is estimated that there are around 6 000 – 8 000 sign language users in Sweden
today who use mobile phones for either SMS or video calls. This project opens a
possibility of using the mobile phone for text calls with other mobile telephones,
with Internet users and traditional text telephones.
There are in addition a large number of users in Sweden today who are classified
as post language deafened, who cannot use sign language and who use speech
for outgoing communication. These users cannot at present use the Internet
efficiently, i.e. say what they want to say and receive text instead of speech.
The emergency number 112 and the Text telephone Relay Service in Sweden are
examples of services that can be reached using a mobile text client or a web-based
client.
Mobile IP Technology
This service addresses a clearly emerging need to communicate using text
communication through the mobile, for example when 3G coverage is lacking or it
is impossible to interface in real time with other text telephones or services which
are compatible with legacy text telephones (V.21, EDT, DTMF, Baudot, V.18, etc.) on
the PSTN network, such as emergency services, text relay services, etc.
To complement the mobile communication, a web-based client is used. Both
clients can be downloaded and used from anywhere, such as Internet cafés, office
environment, etc.
The service supplements existing investments in text and image communication,
e.g. for users who do not use 3G telephones or when coverage for image
communication by 3G does not exist or for deaf adults who do not use sign
language.
The service is also operator independent, which is a big advantage with regard to
the user preferences.
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Call traffic
The following calls can be made using the service.
• Mobile text clients to: legacy text telephones, other mobile text clients
and/or web-based clients that use the open standard specified below
• Web clients to: legacy text telephones, other mobile text clients and/or web-
based clients that use the open standard specified below
• Text telephones: to mobile text clients and/or web-based clients that use the
open standard specified below.
Open standard
The mobile data network puts several constraints that make it almost impossible
for P2P communication between mobile devices. That is the reason for that in the
service it was decided to generate a communication model using standard, existing
and allowed protocols.
The solution adopted in the service is to use an application server that relays the
dataflow between mobile terminals, web interfaces and legacy text telephone.
One of the goals of the service is to allow any software or terminal to connect to
the application server and get the possibilities to communicate with mobile
terminals, web interfaces and legacy text telephone.
The protocol used in the mobile terminals is http(s) and XML-RPC schemas1 that
fulfil the recommendation of the ITU-T T-1402. The web interfaces are using the
http(s) protocol and SOAP-XML web protocol3 that enables the service to use the
protocol and thereby avoid the annoying “firewall” problem, as described in SOAP-
XML4.
1 It’s a specification and a set of implementations that allow software running on disparate operating systems, running in different environments to make procedure calls over the Internet.
2 Mobile text telephone: XML mobile text protocol.
3 SOAP is the Simple Object Access Protocol, a way to create widely distributed, complex computing environments that run over the Internet using existing internet infrastructure. SOAP is about applications communicating directly with each other over the Internet in a very rich way.
4 Web text telephone: SOAP XML web protocol.
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Features
Users who utilize text primarily for remote communication will have good and
equal facilities for effectively contacting each other, authorities or relatives and
alarm services which have a text telephone interface.
A number of important features in the service are discussed below.
Client downloaded to mobile phones and/or PCs
To download the software to be used in the mobile phones:
• The mobile client is downloaded from a specific URL Customers that have
downloaded the software can use it from their mobile phones.
Text client for PC:
• The text client is a Java application accessible via a web page.
Communication with text telephones:
• The service or platform has a so called gateway for communication between
text telephony between mobiles, the Internet and text telephones
• The following gateways are in use today: Sweden (V.21), Denmark (V.21),
Germany (V.18 with EDT text telephones).
Mobile users
The mobile test pilots will send and receive text calls with their mobile phones
which support Java functionality as per MIDP 2.0. For incoming calls it is assumed
that the phone vibrates and depending on whether the user is registered in the
system the call will be initiated by two different user procedures. It is possible to
apply existing T9/dictionary functions in the mobile phone when texting.
The service is also operator-independent, which is a big advantage as far as the
users’ preferences are concerned.
Due to limits in the ergonomics of standard mobile phones available in the market
today, a communication block wise (“chat”) has been chosen.
Voice carry over (VCO) feature cannot be used from the mobile phone because
today’s mobile phones cannot use the data channel and the Internet connection at
the same time.
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Internet users
A web-based client is used by users, relatives, authorities and others to send and
receive text calls from PCs connected to the Internet. The user has to be logged
into the platform in order to be reached.
The web-based client is built as an applet and downloaded directly on the PC. This
means that the users always download the latest version of the client.
The Voice carry over (VCO)/Hear carry over (HCO) features will be implemented
during autumn 2006. The text function in the web client is “character by
character”.
In order for it to be possible to be reached by a web-based client the user or the
relative must register in the service.
Text telephone access
Calls from a traditional text telephone to an Internet client and web/mobile client:
• users who have a traditional V.21 phone (the text telephone user) dial a
fixed-line phone number. The call is automatically answered by the service
• the service answers with the following text, e.g. welcome to web service for
text communication. Which phone number do you want to call?
• the text telephone user then writes the phone number (or name) of the
person sought
• the call will then be connected to the Internet client (web or mobile)
• If the Internet client does not answer the call, the text phone user can leave
a message
• the text telephone user pays the current call charge to the service.
During autumn 2006 the service had approximately 100 registered users using the
service on a daily bases. The field trials with users are continuously evaluated.
Conclusions in the final phase of the project will be vital in the decision making
process within the National Post and Telecom Agency (Post- och telestyrelsen, PTS)
of launching this functionality as a public service in Sweden during 2007.
References and further information
www.flexitext.net
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2.4.3 Mobile text telephony based on
GPRS Communications
Santiago Aguilera
Rationale
Text telephones allow deaf people to communicate remotely. However, even if the
advent of text telephony has brought great improvements in remote
communication for deaf people, current text telephony still has some limitations:
• The need for specific terminals with small production volumes, increasing
production costs in comparison to more widely used terminals
• The fact that deaf people have to pay higher telephone bills. This is due to
the fact that to exchange the same amount of information, text
communications require more time than voice conversations. Since the cost
of a call is charged according to its duration, the cost of text calls is higher
than for voice calls
• Text telephones used in many of the different countries are incompatible,
making it very difficult to establish international text telephone calls.
As previously mentioned, deaf people can be economically discriminated against
due to the higher cost of telephone calls. This is due to the fact that the rates to
be paid depend on the connection time and not on the transmitted data. Therefore,
the objective of this project was to create a text telephony system based on GPRS1
(2.5 G) data mobile communications, because GPRS considers for billing purposes,
only the transmitted information. Since the amount of data is very low in text
conversations (and is independent of the duration) the cost of calls will be much
lower.
For the sake of mobility, the terminals used were Personal Digital Assistants (PDA)
with Pocket PC or Palm operative system. The system was designed using Internet
technology (TCP/IP protocol), allowing communication with any kind of terminals
with the TCP/IP protocol, such as mobile telephones or PCs. For PCs a client text
telephone program was implemented. On the other hand, a WAP text telephone
client, able to communicate with the PDA text telephone client, was developed by
the Spanish Vodafone Foundation.
1GPRS (General Packet Radio Service) run over GSM networks and offer the possibility of charging according to the amount of data sent rather than connection time.
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Previous experience
In order to provide deaf people with the advantages of mobile telephony, in 1998
a commercial terminal, the Nokia 9110 (see figure 2.34), was adapted to text
telephony. This programmable terminal was provided with specific compilers and
its own operating system. The developed programs were therefore not portable
[Roe, 2001].
Figure 2.34 Nokia Communicator working as text telephone.
This text telephone was widely accepted among the deaf community. More than
5 000 terminals are currently being used in Spain. It is worth mentioning that this
project was nominated by European Union as an example of good practice in
eliminating communication barriers and of “Design for All”.
Nevertheless, this terminal was not able to solve two specific problems:
• Text conversations take much more time than voice communications. Since
GSM2 telephony billed users according to the length of the call, deaf people
paid much higher bills
• The software designed for text communication was not portable to new
terminals coming on to the market.
Text Telephone Based on GPRS Mobile Communications
The objective was to apply the new technological solutions that have appeared
over the last few years to solve the previously mentioned problems: high cost of
the calls and dependence on the terminal (no portability).
To solve the first issue, an application based on 2.5 mobile generation (2.5 G) was
designed with the possibility of also using GPRS data communication [Andersson,
2001] [Heine & Sagkob, 2003]. This application allows the customer to be billed
2GSM (Global System for Mobile Communications) is the second generation of mobile phone systems. Invoices are based on connection time.
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only for the amount of information transmitted, which is very low in the case of
text telephony, in comparison to traditional billing based on call duration.
To solve the problem of the dependence on the terminal the application was
programmed in C/C++ for the three different mobile terminal families, which cover
almost 100 % of programmable terminals currently used by the vast majority of
people:
• PDA with Pocket PC [Makofsky, 2003] [Krell, 2002]
• Palm OS [Foster, 2002] [Bachmann, 2002] and
• PC with Windows OS.
Client software
The system has a client/server architecture. The client terminal can be a PDA
(Personal Digital Assistant) or a PC. The software for the client terminal was
designed to allow the user to swap languages. Three languages, Spanish, English
and Portuguese are currently supported. Its main functions are:
• To access GPRS network for connection and obtaining a single IP address for
identification a san IP client on the Internet. This IP address is dynamically
provided by the GPRS network to the different devices connected to it
(figure 2.35)
• To register itself (as a client terminal) in the text telephone server,
communicating the obtained IP address (figure 2.36)
• To allow the user to make a call to other registered terminal
• To inform the user of the calls in the process of being received from other
terminals. For people with hearing difficulties, the indication (event signal) is
visual (blanking the screen terminal) and tactile (activating the vibrator
included in the terminal)
• To register in the user terminal all non answered calls (lost calls)
• The last and most important function is to offer the possibility of real-time
telephone conversation between two users.
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Figure 2.35 PDA connection with GPRS network. Dynamic IP assignation by the GPRS
network. IP is fixed while connection is on.
Figure 2.36 Registration process into the server by a PDA A. This PDA is connected to the
server through the GPRS and Internet networks on a permanent basis (“always-on”) to be
able to access the service at any time.
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Server Software
The server software, running in a remote computer connected to the Internet,
carries out the following functions:
• To allow the registration of the client terminals to be able to communicate
among themselves. This process assumes information is stored in a database
to identify each user: telephone number and IP address assigned by the
GPRS network (figure 2.37)
• To detect the communication request from a caller trying to communicate
with another user. If the called terminal is not registered in the server, the
caller will be warned that no conversation is possible. If the called user is
registered and not busy, he/she will be informed of the caller’s intention to
establish a text conversation with him/her (figure 2.38)
• When a called user accepts an incoming call, and the communication
channel is on, the server drives the information traffic between them (figure
2.39).
Figure 2.37 Call request to the server from a registered PDA A.
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Evolution of Text Telephony
Figure 2.38 Localization of PDA B (call destination) and analysis of its status (no
connected / busy / free) by the PDA A (call origin), through the server.
Figure 2.39 Details of the process in the server during an established conversation
between a PDA A and a PDA B.
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Evaluation
The evaluation phase started at the beginning of 2006. Around 60 PDA terminals
were distributed among deaf users belonging to the Spanish Deaf Organization
Foundation (FCNSE), which was a partner of the project. The objective of the
evaluation was to detect any operational probl