International

Approval of V.18

The following was contributed by Stephen Satchell (Compuserve: 70007,3351) via Bill McGarry at 11 Jul 1994.

I got word from Geneva that the following V-series Recommendations have been approved and are now real:

• V.8 -- Calling-tone menu (part of V.34 startup sequence)
• V.18 -- TDD modulation methods (finally)
• V.34 -- Adaptive rate to 28.8 kilobits/s over switched network
• V.58 -- Network management modem information blocks (MIBs)

The V.18 passage paves the way for inexpensive modems to incorporate support for TDD terminals. This means that modems offering this capability could be used by anyone with a computer terminal to accept indial from a TDD. Conversely, a deaf person can use a standard modem (which implements V.18) in place of a dedicated device.

V.34, aka V.Fast, defines a modem modulation scheme which permits two compliant devices to communicate at a negotiated speed ranging from 4.8 kilobits/s to 28.8 kilobits/s in increments of 2.4 kilobits/s. Further, proper use of the probing tones by the compliant modems permits those modems to select the optimal symbol rate and signal constellation at the beginning of the call. In other modulation methods, the modems had to experiment with the connection in progress to find the optimal equali- zation and speed for a given connection.

V.58 defines a standard way of describing modem capabilities. Originally intended for local area network and wide-area network management, there are people looking to incorporate this system in "desktop managers" as well.

In further news, the AT command set definition is now an offical project (in ITU parlence, there is a Question in the current Study Period) with the goal of defining a new Recommendation V.25 ter. One source has gone out on a limb and said that a ballot could be out as soon as next summer.
My prediction is 18 months.

(c) Copyright Satchell Evaluations 1994 -- The above may be redistribu- ted, but not for profit.

ITU Recommendation V.18 was approved in September 1994. Contact Dick Brandt, [email protected] for more details.

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History of V.18 modems operating in the text telephone mode

History of V.18 Standard

[1] The V.18 standard (V.txp), is the operational and internetworking requirements for modems operating in the text telephone mode.

Background:

[2] When Telephone Administrations were phasing out their low speed printer services some of them made these obsolete electrical terminals available to the deaf community. The technology embedded in these terminals, half duplex, low speed/Baudot (IA2) coding, has been carried through to today in modern TDDs. This adherence to this old technology has greatly limited the deaf community's access to today's on-line information services. In 1991 there was work underway to create a new modern TDD which will incorporate (ASCII (IA5) and a modern modem. One of the major obstacles to movement to this new technology was the need to main6tain compatibility with the large installed base of the older IA2 machines. Any scheme developed for interworking between these new terminals needs to be as automatic as possible as many of the deaf community are older people who would find it difficult to handle complicated set up procedures.

Given the above a study was conducted of an Appendix to Recommendation V.22 bis that would allow for automatic interworking between existing Telecommunications Devices for the Deaf (TDD) terminals and other DTEs using modems conforming to CCITT Recommendations V.22 bis.

The goals were:

1. allow those with existing TDDs to interconnect and communicate with a larger range of people and services.
2. allow for gradual phasing in of new TDDs equipped with V.22 bis modems.

Considerations of the Study:

1. Older TDDs (prior to V.22) use 1800 Hz/1400 Hz FSK half-duplex operation with an approximate baud rate of 45.5 in the U.S.A. and 50 in Europe.
2. IA2/IA5 conversion should take place in the modem. (5 bit Baudot to 7 bit ASCII)
3. Signal, generated by the calling party, is needed as the phone may be answered by a "hearing" person who needs to be aware this is a TDD call. (V.25 calling tone?)
4. The protocol developed is able to accommodate extended quiet periods at the beginning of the sessions as in many cases the deaf person using an older TDD may not be aware the called party has answered or there may be a delay going from the voice mode to the TDD mode (many existing TDDs are acoustically coupled).

Recommendation for doing the study:

Community leaders through the world have recognized that the deaf community needs to be allowed to participate in the "Information Age" through improved access to the growing number of on-line information services available as well as the ability to communicate with hearing friends through home PCs. This should not require them to incur the expense of having two terminals/modems: one for communicating with TDDs and one for other services. This latter concern also applies to many hearing people who would like to be able to communicate with their hearing impaired friends without the complication and expense of acquiring an switching between two separate modems.
CCITT is in the unique position to help the deaf community by providing an international solution to this problem. It was therefore recommended that CCITT undertake the study of developing a "Procedure for automatic interworking (Automoding) between Recommendation V.22 bis modems and TDDs. The use of Recommendation V.22 bis modems was proposed as they were becoming the "standard" modem for most on-line applications, as well as PC-based communications at the time.

As a result of the study, The XVII Study Group then produced what is called the V.18 standard. The Final Draft of the Recommendation V.18 was submitted for approval Geneva 1-9 June 1994.

At the Meeting , all 15 Members present proposed that the approval procedure be initiated.

sources:
I would like to thank Texas Instruments Incorporated and Augment Systems Incorporated for the information.

1. Proposed approval of four new Recommendations agreed to by Study Group 14 at its meeting on 9 June 1994, International Telecommunications Union, Telecommunication Standardization Bureau, Geneva, 20 June 1994, ref TSB Circular 82 COM 14/YS, signed by Th. Irmer, Director of the Telecommunications Standardization Bureau

2. Telecommunications Device Devices for the Deaf (TDD)/V.22 bis, CCITT Interworking Study Group XVII Delayed Contribution D93 Geneva 29 April-3 May 1991

3. Final Draft of Recommendation V.18, Study Group 14/WPS Rapporteur on Question 8/14 (Mr. R.P. Brandt, U.S.A. Geneva, 1-9 June 1994

(Contributed by Stephen Pomfret, Augment Systems, 19 Crosby Drive, Bedford MA 01730-1419, TDD (617)275-4510 at 28 Oct 1994.)

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USA

New standard: Bell 103, ASCII, 300 BPS, 8N1
Old standard: Weitbrecht, Baudot, 45.5 BPS

A reference for the old standard:
EIA STANDARDS PROJECT PN-1663
TELECOMMUNICATION DEVICES FOR THE DEAF
DRAFT 9
JUNE, 1986
Prepared by the EIA Engineering Committee TR-41
Ad Hoc Committee on Telecommunication Devices for the Deaf

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Great Britain

Contributed by Andrew J. Cowie at 1997 January 01.

Preferred standard : - CCITT V.21 300bps 8N1
Also in use        : - Baudot 45.45bps

Notes:

Most TTYs in use in the UK are imported Ultratec products, which offer ITU-T V.21 @ 300 bps (NB! NOT Bell 103!), and Baudot 45.45bps, and most models have some autoswitching between Baudot and CCITT. The level of sophistication of the autoswitching is higher in the newer models.

Some older textphones in use in the UK are V.21 Only, or V.23 mode 2 (1200/75 bps) only. New purchase of such machines is discouraged, and the latter can now only be used to contact the National Relay Service ("Typetalk").

The main UK relay is currently ITU-T V.21, V.22, and V.23 compatible only, no Baudot support, although this is planned. The UK relay service also provides access to the Emergency Services through a dedicated, high priority number. This number supports the same ITU-T standards as the main relay PLUS Baudot.

UK Relay contact Information:

     RNID Typetalk
     John Wood House
     Glacier Building
     Harrington Road
     Brunswick Business Park
     Liverpool
     L3 4DF
     Great Britain

     +44 151 709 9494 Voice
     +44 151 709 8119 Fax
     0800 592 600 Technical Support (Textphones only)
     0800 500 888 Registrations (Textphones only)
     0800 592 593 Billing/Rebates (Textphones only)

     0800 51 51 52 Relay calls (voice callers)
     (+44 151 494 2022 from outside UK)
     0800 95 95 98 Relay calls (CCITT textphones only)
     (+44 151 494 1260 from outside UK)
     0800 112 999  EMERGENCY SERVICES (CCITT/Baudot textphones only)

     NB - 0800 numbers can only be dialled from within the UK.

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Israel

Contributed by Omer Zak:

FAX machines are being used. For modem conversations, use the following: Bell 103, ASCII, 300 BPS, 8N1. The Hebrew letters are encoded according to Israeli Standard 960.

A copy of the proposed Israeli TDD standard is available in the Deaf Gopher. To access a short summary, click here.

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New Zealand

Contributed by Barry Kirkland:

Baudot, I'd say, but it's a bit of a monkey's jungle like it is in America and England. I don't know if ASCII is in wide use in NZ.

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[Other countries - please give information.]

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WHAT YOU NEED TO SET UP A TWO LINE VCO CALL

1. Two separate phone lines
2. A telephone plan purchased from your Local Exchange Carrier with three-way calling (also known as conference)
3. A direct connect ASCII TTY or PC equipped with a modem

STEPS TO FOLLOW WHEN MAKING A TWO LINE VCO CALL

1. Call TRS on DATA line using ASCII TTY or PC
2. Type to Communications Assistant (CA) that this will be a two line VCO call
3. Instruct CA to call you on other phone (VOICE)
4. Answer the voice line with your voice (to allow the CA to distinguish your voice from other voices) and tell CA you will be conferencing another person into the call, and NOT to type your speech at all!!!!
5. On voice line, say `Please hold' to the CA
6. Press FLASH or HOLD on phone
7. Dial the number of the person you want to call on VOICE line
8. Press CONFERENCE or whatever is the button for three way calling.

When the called party answers, the CA will immediately start typing. So as soon as you see `Hello' or whatever is on the DATA line, you can start talking. Moreover the other person has no idea that you are using TRS. The CA will type only the other person's speech which is read on the DATA line.

NO NEED FOR THAT TIME CONSUMING `GA' or `GO AHEAD'.......

The CA will NOT communicate with the third party but the CA will indicate if the third party is talking too fast or whatever thus you would have to ask the third party to slow down i.e. you are in control of the whole process.

The caller also has the flexibility of hanging up on the called party without losing connection with the CA. An additional advantage is that it will be easier to deal with pre-programmed dialing for calling cards, 900 numbers, automated recorded menus etc.

Most offices have the facilities that allow two-line VCO to work so make use of these before you decide to make the investment of a second phone at home.

For those of you with hearing aids or cochlear implants, this can also provide excellent auditory training.

Contact information

Stephanie Buell of the Wisconsin TRS can be contacted at:
TTY 608 833-3898
FAX 608 833-3208
Internet [email protected]

(Contributed by Tilak Ratnanather [email protected] at 22 Aug 1994.)

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