When, in 1988, IBM Corp admitted defeat and sold most of the Rolm Corp telecommunications subsidiary that it had bought just four years previously, the effort to wed the computer to the PABX seemed moribund. The technological convergence that IBM had foreseen hadn’t happened and the importance of the PABX in offices was seen to be dwindling in favour of the fast-growing local area network. There was also the problem of Rolm and IBM’s conflicting corporate style. It was not, in short, destined to work and in whodunnit parlance IBM had neither the motive, the means nor the opportunity. But just three years on, announcements last week from a clutch of computer and PABX suppliers – including IBM, AT&T, Ericsson, DEC and Stratus signalled a resurgence of interest.

Identified Market

Not only have the chaps in marketing at long-last identified a cohesive group of punters that want the innovative services that a computer-PABX alliance can bring, but the technology and standards are making progress as well. The actual delivery of the Integrated Services Digital Network has been one of the factors driving this recovery. While much of the interest in the technology has focussed on its speedy transmission rates and call set-up, it is the extra information provided by ISDN’s supplementary services that has proved most fruitful when designing new services. One of the new facilities that the supplementary services give to a telephone is the ability to display the number of the person that is ringing before the phone is picked up. Service organisations such as credit card companies have fallen in love with the idea, realising that – if only they could link their computers to their PABX – it would be possible to pull up customer records automatically as the customers called in. Of course there would be the odd mismatch, but it is assumed that significant time savings could be made this way. Certainly this is the market that the various companies kept plugging during their separate announcements. IBM’s came as part of the huge set of announcements reported recently in Computergram. In 1989 the company introduced CallPath, a product that linked System/370 machines to the Rolm 9750 PABX; later the concept was broadened into the CallPath services architecture – a generic method of linking its computers and a variety of PABXs – and introduced CallPath/400 for its mid-range machine. Last March saw the addition of CallPath CICS/MVS in Europe. Announced a month ago was that this last product was available globally; also introduced at that time was a version for VSE. The glue that holds all of this together is the CallPath Switchserver/2, a gateway product designed to handle switch protocol conversion, freeing applications developers from this onerous task. As a result, IBM claims to be able to support Northern Telecom Ltd’s Meridien 1, AT&T Co’s Definity Generic 2 and the NEC Corp APEX/NEAX 2000 information management systems, in addition to its own and those from Siemens AG and Rolm.

By Chris Rose

The absence of GEC-Plessey Telecommunications Ltd is disappointing to users in the UK but all that IBM will say is that it is actively working to extend the list. But if ISDN has filled one technical hole – in that the public network can now provide information that is actually worth processing – the other market requirement is a standard to link computers and PABXs. Resigned groans will meet the news that there is not one but two standards currently being developed on either side of the Atlantic. The European Computer Manufacturers Association is working on its Computer Supported Telecommunications Applications, CSTA, standard, while in the US ANSI is busy developing its own switch computer application interface, SCAI. Both are essentially OSI applications sitting at Layer Seven in the model; both have yet to be finished, although their foundations are strong enough to encourage vendors to begin using them. CSTA suffered a temporary setback this month when the European association’s TC32 committee sent the standard back to its workgroup for ame

ndments, when many observers had expected a rubber stamping operation. A meeting of the European organisation was considering the standard last week. Meanwhile, the switch-computer application-interface is due to become ANSI standard in the first quarter of 1992. There is no getting away from the fact that the two standards are competing for the same patch, although Christopher Foard, supervisor in AT&T Bell Laboratories’ PABX-host group says they do have their differences. The company’s involvement in the application interface means that it has much more of a public network flavour, says Foard, while CSTA’s strength is its rich interface between private exchanges and computers. Nevertheless, overlap there is, and it seems likely that at some future date ISO will be faced with submissions from ECMA and ANSI, and will have to make a choice. In the meantime, manufacturers have to choose which to support. When AT&T announced its own CallVisor Adjunct Switch Applications Interface, ASAI, recently, it was clear it was supporting both, and yet neither.

Standards mess

ASAI, says the company, is closely aligned with both, though Foard says it was closer to CSTA – the more complete of the two. The hybrid has attracted a good deal of interest however Stratus Computer Inc announced support via it’s Stratus Adjunct Interface, DEC said that its Computer Integrated Telephony package would get an AT&T interface and IBM said that the CallPath Switchserver/2 would too. You will even be able to get a protocol analyser and simulator for the protocol, following the announcement from Calabasas, California-based Tekelec Inc that it will add the ASAI applications interface to its Chameleon 32 analyser. At the same time, however, DEC also announced support for a native CSTA standard-based system. Despite the holes in the standard, when Stockholm-based L M Ericsson Telefon AB announced links between its MD110 exchange and DEC’s CIT version 3, the link was based on CSTA and the product is due to ship early next year. All in all, the standards-making process is still in a mess, though the effort that is going into tidying it up is encouraging. Success will mean computer and telecommunications companies can continue to focus on what they know best, without feeling that they have to plunge into a foreign sector like IBM tried to do. And while the PABX may never become the centre of an office automation strategy, prospects look good for intelligent co-operation between the twin worlds of voice and data.