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International standards for teletex
As teletexservicesdevelop,the differentsuppliers are recognizingthe need for worldwide communicationsstandards.Now that priceshave been decided,what benefitsdoes teletexhave for an organization?
International standardsfor teletex by R J FIRTH
T
he familiar concepts of the office are constantly changing, with the traditional framewo:: of telephones, typewriters and telex machines being supplemented or in some instances replaced, by word processors, small business machines, and integrated office systems. The bulk of the technology required for the electronic office does already exist. However, it is only through effective communications that the full benefits can be achieved, and teletex will undoubtedly be a principal factor in this process. Teletex is a text communication service allowing the transfer of letter quality documents on an international Abstract: Teletex allows the transfer of letter quality documents on an international basis between terminals supplied by different manufacturers. The paper descn’bes internationalagreements covering the standardizationof teletex transmission, the costsand advantages of teletex, and provides a review of the likelyfuture developments in this field. Keywords: teletex, telecommunications, communication standards. R J Firth is a senior consultant in the office systems division at the National Computing Centre.
~0125 no 10
decemher
1983
0011-684X/83i100021-04$03.00
0
1983 Butterworth
basis, between terminals supplied by different manufacturers but with compatibility ensured.. The choice of t.erminology is perhaps unfortunate since we already have teletext, e.g. in the UK, Ceefax and Oracle, and undoubtedly leads to confusion for the noninformed. Referring to the service as ‘super telex’ is similarly misleading since its significance is far more fundamental than being just an enhanced telex service, and has perhaps more affinity to communicating word processors, but without the problems of supplier incompatability.
International
agreements
The CCITT recommendations for teletex will enable the provision of a worldwide service for correspondence to be sent and received automatically, respecting both the content and the layout of the text. Communication takes place between the memory of one terminal and the memory of another, enabling other activities to be performed at the terminal, e.g. text preparation, without interruption. All terminals on the: teletex service must behave according to a basic set of rules, to ensure compatibility. However, terminals can be a number
& Co (Publishers)
Ltd.
21
of different types, e.g. word processor typewriters or even type, electric mainframe computer terminals, giving the user the advantage of being able to select equipment with the required amount of sophistication. Although the rules defining the character set, the control functions, and other characteristics of terminals are defined in CCITT recommendations, they do allow bodies responsible for the communication networks in each individual country enough freedom to introduce a teletex service which matches the local telecommunications and terminal supply environment. In the UK, British Telecom (BT) have specified that the service will utilize the existing communication networks, PSTN and PSS, and the customer will have the choice of obtaining approved terminals directly from equipment manufacturers and distributors, whereas, in other countries, a closed approach has been adopted with terminals supplied through PTTs. The international agreements for teletex have the following underlying principles: A basic level of compatibility is provided between all terminals participating in the service. There is no restriction on the type of network used, it is up to each telecommunications authority to decide on, the networks on which the service is to be carried. The page is the basis for text formatting and text transmission. The character repertoire of 308 characters caters for all latin-based languages, including upper and lower case letters, punctuation marks, numerics, currency signs and other miscellaneous symbols. A keyboard that can generate only a subset of the full teletex character repertoire is acceptable as a source of text input, although terminals must have the ability to receive into store the full range of the basic character repertoire.
22
The service normally operates on a fully automatic basis and is open continuously. Local mode operation, text preparation, editing, printing etc., is not normally disturbed by the transmission or receipt of correspondence. Received correspondence can be printed or displayed on a screen. If printed, the document is identical to that produced by the sender as far as content, layout and format are concerned. Facilities to provide a permanent copy of every message should exist at every teletex installation. There is no restriction on private use applications such as encryption. Inter-working in both directions with the telex service is to be provided. Standard options outside the basic standard can be accommodated, e.g. different line spacings, special character sets, different printable areas. The basic page format is defined by the printable area common to A4 and the US paper size, with both vertical and horizontal page orientations catered for. Recommendations for modem requirements will enable transmission rates of up to 2400 bit/s (250 c/s). costs Many observers feel that the development of the teletex service will be dependent on the costs of utilizing the service, and, in particular, the capital cost of teletex terminals. Teletex communication capability will embrace a wide spectrum of types of equipment, from electric typewriters, through word processors to teletex store and forward systems, and there will, therefore, be a broad range of prices in relation to these products. Prices for dedicated teletex terminals are likely to start in the region of E3000, rising to around
f50000 for sophisticated teletex management facilities. The cost of actually subscribing to the service has not as yet been fixed by BT but is likely to be in the region of &25 as an initial subscription charge. In addition, other charges yet to be fixed are for directory insertions, conversion facility and gateway charges, e.g. for connecting to the telex network. Standard charges will be incurred for line use and calls. For lines, the charges will be standard charges appropriate to the network used. For use of PSTN, the normal business exchange telephone line rental will apply, and for PSS, the normal dataline rental applies. For call charges, again the standard charges for calls on the appropriate network will apply. The choice of whether PSTN- or PSS-based terminals would be most cost effective will depend largely on the volume of mail to be transmitted. Generally speaking, annual charges for access to PSTN are cheaper than PSS, but PSS call charges are lower for a given volume of text. Larger users should find PSS cheaper and low volume users will find PSTN more cost effective, with the breakeven point varying depending on the distribution of long distance and local messages, and whether advantage can be taken of cheaper off peak tariffs for overnight delivery.
Advantages
of teletex
As the teletex service develops it is undoubtedly going to affect traditional forms of business communication, such as surface mafl, telex, and communicating word processors. Surface mail has a number of favourable points which are sufficient to ensure its use (although declining) for some years to come, notably: Communication can be established between any organization worldwide, with no need for special equipment. Delivery is relatively assured. Document length is not restricted.
data processing
l
The process of establishing communication is well understood.
However, l l l
delivery delivery delivery
with teletex: is guaranteed is faster can be cheaper
(see Table
1) Table 1. Number of teletex pages that can be sent in the UK for SO.16 (i.e. the cost of a first class stamp)
Pages (approx) Cheap Standard Peak rate rate* rate ~-local call calls over 56krn
273
67
51
24
6
4
*Rates depend on time of day.
Within an organization teletex could also replace the manual systems of distributing messages and reports by internal messenger service. Text for internal use could exist electronically, created, transmitted and stored in a far more efficient manner.
Comparison with telex and communicating word processors The motivation behind the development of teletex is best illustrated by comparing the capabilities of teletex with the telex service and communicating word processors, as it is from these that the principles of teletex evolved. Telex is an international text communication service that has been well used for many years and despite its drawbacks is still growing. Telex is the subject of international agreements and has a large population of terminals with over a million subscribers worldwide. Telex numbers are available from world directories and messages can be received whilst a terminal is unattended. Telex meets a communication need because it works to agreed standards and has a good coverage of users. However, teletex is also able to satisfy the above
~0125 no 10
december
1983
criteria, but without the disadvantages that exist with the telex service. The telex service is slow, with a limited character set, limited error checking capability and the setting up of a call is essentially a manual process. Transmission of text is slow at 50 bit/s, around 6c/s, and the character set consists of upper case only. Characters are inclined to be dropped from, or changed during, transmission, and the sending of a message is often hampered by receiving terminals being in use, or international lines being engaged. Word processors, on the other hand, have a character set required for business correspondence and have high quality presentation. In addition to performing local office functions, communicating word processors are capable of fast transmission of text documents. There are, however, few agreed standards for word processing communications, word processor characters, or function coding. This is reflected in the fact that currently only approximately 3% of word processors are bought for the purpose of communicating. Perhaps a larger percentage are purchased with some undefined intention to eventually communicate, only to find then that they will not.
Standards A service such as teletex would not be possible as a national or international service without some level of standardization. Unrestricted development without standards could lead to different applications and independent proprietary solutions which would be incompatible. Such a development would be to the disadvantage of the user, the manufacturer and the network provider. The existing recommendations for teletex services were developed by a CCITT study group and were ratified in November 1980. These are published in the current issue of their four yearly volumes of recommendations, and are covered by:
F200 teletex service S60 teletex terminal S61 character repertoire
and cod-
ing teletex procedures transport service By the use of common protocols, and terminals where interworking has been considered from the outset, users will have the benefit of choosing from a range of terminals and systems which are able to meet their requirements and will simplify international communications. Manufacturers will have a larger market for communicating terminals with common standards for manufacture, and carriers, by providing network facilities, will obtain increased call revenue.
International
developments
Teletex is an international standard, and as such will eventually be used worldwide, gradually displacing the use of telex. This process will not happen overnight, and it will be many years before telex becomes finally redundant. There are gateway exchanges to be bu.ilt to cater for international teletex communication and interworking with the telex network, and the introduction of teletex does present some economic and political problems that need to be overcome. In addition, there is significant investment in tele:x networks and terminals which cannot be written off too soon. International teletex facilities will be introduced through a series of bilateral agreements. CCITT recommend that wherever possible, existing international circuits should be used such as IPSS. The freedom in the choice of networks which was necessary to encourage the speedy introduction of national services, has created certain incompatibilities between those services. However, without underestimating the technical and administrative problems involvled, the incom-
23
Figure 1. Options in international telex. patibilities are capable of being solved by modern microprocessor-based gateways, which can bridge basic differences between services, all of which remain completely transparent to the teletex user. Figure 1 illustrates some of the possibilities for international teletex working. Activity on implementing teletex services is currently centred on Europe, with West Germany being Table 2. Countries that have announced a teletex service
Country
Service Interface start date standard
UK GermanY Sweden Austria Belgium France Luxembourg Denmark Italy Spain Norway
1984 1982 1982 1984 1984 1984 1984 1984 1984 1984 1984
Netherlands Switzerland FGre Canada South Africa Finland
1984 1984 1984 1984 1984 1985
24
x.25 x.21 x.21 x.25 x.25 x.25 x.21 x.25
x.25 x.21 X.25 x.21
the most developed with around 3 500 subscribers. However, outside of Europe, Canada and South Africa have announced plans for the introduction of teletex, and will be two of the next countries to implement the service. Table 2 shows the countries with announced plans for teletex and the likely start date for the provision of the service. As stated above, there are national variations between countries, and any delay in the provision of international coverage may have an impact on the strategy adopted by multinational organizations who are looking for solutions to corporate communication problems. However, national variations of services, and the consequent disadvantages to users and manufacturers, must be viewed in the light of existing or impending national services. Had the CCITT recommendations given no freedom of choice as to the network type, modem type etc., then considerably fewer services would be being planned, and the prospect of full international working would be remote. Future developments Further teletex developments are being planned and a number of enhancements are currently being studied by the CCITT, which should be ratified at the next plenery session in 1984. These enhancements include mixed mode working, interworking with facsimile, message handling and database access. The aim is to allow the addition of graphics, signatures, company logos, diagrams using facsimile, and to allow access to databases in an interactive mode. At the same time, care will be taken to ensure that the basic teletex terminals are not burdened with additional complexities and costs, when enhancements are not needed by users. Regardless of the levels of sophistication reached, the basic service will not become obsolete, and users will be
able to use basic terminals alongside more advanced terminals as these become available. The communication protocols for teletex are relatively complicated, and the technology required of the terminals is advanced, but because existing networks can be used, the task of organizing a teletex service is essentially an administrative one, i.e. ensuring a supply of terminals which exhibit the minimum required characteristics; providing gateways for international connections and telex interworking; and then administering the service by organizing the allocation of terminal identity codes and the provision of directories. In the UK, there is much to be done on increasing awareness of what teletex is and the benefits to be obtained by its use. The Department of Trade and Industry is currently funding a major teletex awareness scheme, which includes offering 50% subsidies for companies purchasing teletex equipment from designated suppliers between October 1983 and 30 June 1984. The suppliers on this list are Ferranti, STC, Plessey and Reliance. The NCC also intends to contribute to improving awareness, by producing publications during 1984 aimed at giving practical guidelines for organizations evaluating teletex equipment and implementing teletex. Although the feeling is that there may be an initial reluctance for organizations to subscribe to the service during the early part of 1984. When interworking with the telex network becomes available, in mid-1984, then this will provide the terminal population base needed for many companies to be able to justify investment in teletext, and as the population of teletex terminals grows, then these companies will be in a position to exploit to the full, the capabilities that teletex offers. q The National ComputingCentre Ltd, Oxford Road, Manchester Ml 7ED, UK. Tel: 061-228 6333.
data processing
International standardsfor teletex by R J FIRTH
T
he familiar concepts of the office are constantly changing, with the traditional framewo:: of telephones, typewriters and telex machines being supplemented or in some instances replaced, by word processors, small business machines, and integrated office systems. The bulk of the technology required for the electronic office does already exist. However, it is only through effective communications that the full benefits can be achieved, and teletex will undoubtedly be a principal factor in this process. Teletex is a text communication service allowing the transfer of letter quality documents on an international Abstract: Teletex allows the transfer of letter quality documents on an international basis between terminals supplied by different manufacturers. The paper descn’bes internationalagreements covering the standardizationof teletex transmission, the costsand advantages of teletex, and provides a review of the likelyfuture developments in this field. Keywords: teletex, telecommunications, communication standards. R J Firth is a senior consultant in the office systems division at the National Computing Centre.
~0125 no 10
decemher
1983
0011-684X/83i100021-04$03.00
0
1983 Butterworth
basis, between terminals supplied by different manufacturers but with compatibility ensured.. The choice of t.erminology is perhaps unfortunate since we already have teletext, e.g. in the UK, Ceefax and Oracle, and undoubtedly leads to confusion for the noninformed. Referring to the service as ‘super telex’ is similarly misleading since its significance is far more fundamental than being just an enhanced telex service, and has perhaps more affinity to communicating word processors, but without the problems of supplier incompatability.
International
agreements
The CCITT recommendations for teletex will enable the provision of a worldwide service for correspondence to be sent and received automatically, respecting both the content and the layout of the text. Communication takes place between the memory of one terminal and the memory of another, enabling other activities to be performed at the terminal, e.g. text preparation, without interruption. All terminals on the: teletex service must behave according to a basic set of rules, to ensure compatibility. However, terminals can be a number
& Co (Publishers)
Ltd.
21
of different types, e.g. word processor typewriters or even type, electric mainframe computer terminals, giving the user the advantage of being able to select equipment with the required amount of sophistication. Although the rules defining the character set, the control functions, and other characteristics of terminals are defined in CCITT recommendations, they do allow bodies responsible for the communication networks in each individual country enough freedom to introduce a teletex service which matches the local telecommunications and terminal supply environment. In the UK, British Telecom (BT) have specified that the service will utilize the existing communication networks, PSTN and PSS, and the customer will have the choice of obtaining approved terminals directly from equipment manufacturers and distributors, whereas, in other countries, a closed approach has been adopted with terminals supplied through PTTs. The international agreements for teletex have the following underlying principles: A basic level of compatibility is provided between all terminals participating in the service. There is no restriction on the type of network used, it is up to each telecommunications authority to decide on, the networks on which the service is to be carried. The page is the basis for text formatting and text transmission. The character repertoire of 308 characters caters for all latin-based languages, including upper and lower case letters, punctuation marks, numerics, currency signs and other miscellaneous symbols. A keyboard that can generate only a subset of the full teletex character repertoire is acceptable as a source of text input, although terminals must have the ability to receive into store the full range of the basic character repertoire.
22
The service normally operates on a fully automatic basis and is open continuously. Local mode operation, text preparation, editing, printing etc., is not normally disturbed by the transmission or receipt of correspondence. Received correspondence can be printed or displayed on a screen. If printed, the document is identical to that produced by the sender as far as content, layout and format are concerned. Facilities to provide a permanent copy of every message should exist at every teletex installation. There is no restriction on private use applications such as encryption. Inter-working in both directions with the telex service is to be provided. Standard options outside the basic standard can be accommodated, e.g. different line spacings, special character sets, different printable areas. The basic page format is defined by the printable area common to A4 and the US paper size, with both vertical and horizontal page orientations catered for. Recommendations for modem requirements will enable transmission rates of up to 2400 bit/s (250 c/s). costs Many observers feel that the development of the teletex service will be dependent on the costs of utilizing the service, and, in particular, the capital cost of teletex terminals. Teletex communication capability will embrace a wide spectrum of types of equipment, from electric typewriters, through word processors to teletex store and forward systems, and there will, therefore, be a broad range of prices in relation to these products. Prices for dedicated teletex terminals are likely to start in the region of E3000, rising to around
f50000 for sophisticated teletex management facilities. The cost of actually subscribing to the service has not as yet been fixed by BT but is likely to be in the region of &25 as an initial subscription charge. In addition, other charges yet to be fixed are for directory insertions, conversion facility and gateway charges, e.g. for connecting to the telex network. Standard charges will be incurred for line use and calls. For lines, the charges will be standard charges appropriate to the network used. For use of PSTN, the normal business exchange telephone line rental will apply, and for PSS, the normal dataline rental applies. For call charges, again the standard charges for calls on the appropriate network will apply. The choice of whether PSTN- or PSS-based terminals would be most cost effective will depend largely on the volume of mail to be transmitted. Generally speaking, annual charges for access to PSTN are cheaper than PSS, but PSS call charges are lower for a given volume of text. Larger users should find PSS cheaper and low volume users will find PSTN more cost effective, with the breakeven point varying depending on the distribution of long distance and local messages, and whether advantage can be taken of cheaper off peak tariffs for overnight delivery.
Advantages
of teletex
As the teletex service develops it is undoubtedly going to affect traditional forms of business communication, such as surface mafl, telex, and communicating word processors. Surface mail has a number of favourable points which are sufficient to ensure its use (although declining) for some years to come, notably: Communication can be established between any organization worldwide, with no need for special equipment. Delivery is relatively assured. Document length is not restricted.
data processing
l
The process of establishing communication is well understood.
However, l l l
delivery delivery delivery
with teletex: is guaranteed is faster can be cheaper
(see Table
1) Table 1. Number of teletex pages that can be sent in the UK for SO.16 (i.e. the cost of a first class stamp)
Pages (approx) Cheap Standard Peak rate rate* rate ~-local call calls over 56krn
273
67
51
24
6
4
*Rates depend on time of day.
Within an organization teletex could also replace the manual systems of distributing messages and reports by internal messenger service. Text for internal use could exist electronically, created, transmitted and stored in a far more efficient manner.
Comparison with telex and communicating word processors The motivation behind the development of teletex is best illustrated by comparing the capabilities of teletex with the telex service and communicating word processors, as it is from these that the principles of teletex evolved. Telex is an international text communication service that has been well used for many years and despite its drawbacks is still growing. Telex is the subject of international agreements and has a large population of terminals with over a million subscribers worldwide. Telex numbers are available from world directories and messages can be received whilst a terminal is unattended. Telex meets a communication need because it works to agreed standards and has a good coverage of users. However, teletex is also able to satisfy the above
~0125 no 10
december
1983
criteria, but without the disadvantages that exist with the telex service. The telex service is slow, with a limited character set, limited error checking capability and the setting up of a call is essentially a manual process. Transmission of text is slow at 50 bit/s, around 6c/s, and the character set consists of upper case only. Characters are inclined to be dropped from, or changed during, transmission, and the sending of a message is often hampered by receiving terminals being in use, or international lines being engaged. Word processors, on the other hand, have a character set required for business correspondence and have high quality presentation. In addition to performing local office functions, communicating word processors are capable of fast transmission of text documents. There are, however, few agreed standards for word processing communications, word processor characters, or function coding. This is reflected in the fact that currently only approximately 3% of word processors are bought for the purpose of communicating. Perhaps a larger percentage are purchased with some undefined intention to eventually communicate, only to find then that they will not.
Standards A service such as teletex would not be possible as a national or international service without some level of standardization. Unrestricted development without standards could lead to different applications and independent proprietary solutions which would be incompatible. Such a development would be to the disadvantage of the user, the manufacturer and the network provider. The existing recommendations for teletex services were developed by a CCITT study group and were ratified in November 1980. These are published in the current issue of their four yearly volumes of recommendations, and are covered by:
F200 teletex service S60 teletex terminal S61 character repertoire
and cod-
ing teletex procedures transport service By the use of common protocols, and terminals where interworking has been considered from the outset, users will have the benefit of choosing from a range of terminals and systems which are able to meet their requirements and will simplify international communications. Manufacturers will have a larger market for communicating terminals with common standards for manufacture, and carriers, by providing network facilities, will obtain increased call revenue.
International
developments
Teletex is an international standard, and as such will eventually be used worldwide, gradually displacing the use of telex. This process will not happen overnight, and it will be many years before telex becomes finally redundant. There are gateway exchanges to be bu.ilt to cater for international teletex communication and interworking with the telex network, and the introduction of teletex does present some economic and political problems that need to be overcome. In addition, there is significant investment in tele:x networks and terminals which cannot be written off too soon. International teletex facilities will be introduced through a series of bilateral agreements. CCITT recommend that wherever possible, existing international circuits should be used such as IPSS. The freedom in the choice of networks which was necessary to encourage the speedy introduction of national services, has created certain incompatibilities between those services. However, without underestimating the technical and administrative problems involvled, the incom-
23
Figure 1. Options in international telex. patibilities are capable of being solved by modern microprocessor-based gateways, which can bridge basic differences between services, all of which remain completely transparent to the teletex user. Figure 1 illustrates some of the possibilities for international teletex working. Activity on implementing teletex services is currently centred on Europe, with West Germany being Table 2. Countries that have announced a teletex service
Country
Service Interface start date standard
UK GermanY Sweden Austria Belgium France Luxembourg Denmark Italy Spain Norway
1984 1982 1982 1984 1984 1984 1984 1984 1984 1984 1984
Netherlands Switzerland FGre Canada South Africa Finland
1984 1984 1984 1984 1984 1985
24
x.25 x.21 x.21 x.25 x.25 x.25 x.21 x.25
x.25 x.21 X.25 x.21
the most developed with around 3 500 subscribers. However, outside of Europe, Canada and South Africa have announced plans for the introduction of teletex, and will be two of the next countries to implement the service. Table 2 shows the countries with announced plans for teletex and the likely start date for the provision of the service. As stated above, there are national variations between countries, and any delay in the provision of international coverage may have an impact on the strategy adopted by multinational organizations who are looking for solutions to corporate communication problems. However, national variations of services, and the consequent disadvantages to users and manufacturers, must be viewed in the light of existing or impending national services. Had the CCITT recommendations given no freedom of choice as to the network type, modem type etc., then considerably fewer services would be being planned, and the prospect of full international working would be remote. Future developments Further teletex developments are being planned and a number of enhancements are currently being studied by the CCITT, which should be ratified at the next plenery session in 1984. These enhancements include mixed mode working, interworking with facsimile, message handling and database access. The aim is to allow the addition of graphics, signatures, company logos, diagrams using facsimile, and to allow access to databases in an interactive mode. At the same time, care will be taken to ensure that the basic teletex terminals are not burdened with additional complexities and costs, when enhancements are not needed by users. Regardless of the levels of sophistication reached, the basic service will not become obsolete, and users will be
able to use basic terminals alongside more advanced terminals as these become available. The communication protocols for teletex are relatively complicated, and the technology required of the terminals is advanced, but because existing networks can be used, the task of organizing a teletex service is essentially an administrative one, i.e. ensuring a supply of terminals which exhibit the minimum required characteristics; providing gateways for international connections and telex interworking; and then administering the service by organizing the allocation of terminal identity codes and the provision of directories. In the UK, there is much to be done on increasing awareness of what teletex is and the benefits to be obtained by its use. The Department of Trade and Industry is currently funding a major teletex awareness scheme, which includes offering 50% subsidies for companies purchasing teletex equipment from designated suppliers between October 1983 and 30 June 1984. The suppliers on this list are Ferranti, STC, Plessey and Reliance. The NCC also intends to contribute to improving awareness, by producing publications during 1984 aimed at giving practical guidelines for organizations evaluating teletex equipment and implementing teletex. Although the feeling is that there may be an initial reluctance for organizations to subscribe to the service during the early part of 1984. When interworking with the telex network becomes available, in mid-1984, then this will provide the terminal population base needed for many companies to be able to justify investment in teletext, and as the population of teletex terminals grows, then these companies will be in a position to exploit to the full, the capabilities that teletex offers. q The National ComputingCentre Ltd, Oxford Road, Manchester Ml 7ED, UK. Tel: 061-228 6333.
data processing