e-phone Evolution:
BT Re-creates the Payphone

John Bassett, BT Payphones

When we began the specification process for a public-access Internet payphone, we realized that the design issues were quite different from those of any previous payphone we had developed. The specs called for a device, dubbed the Multiphone, that would offer standard telephony as well as web surfing, email, and printing. Connected via ISDN, it would need a display screen, a keyboard, and a printer, as well as a normal telephone handset.

On its own, the Multiphone's design might seem simple enough - although it's obviously more complex than the standard ruggedized telephone found in a UK phone kiosk. But our engineers also needed to consider how they could upgrade the phone at hundreds of locations throughout the UK - frequently and cost-effectively - as new Internet protocols and data delivery mechanisms became available.
Initial design

Our engineering team used Windows NT as the operating system for our first prototype. It was chosen at this stage because:

• NT was well-known to our senior management
• our team was familiar with the Microsoft API
• it offered a great deal of out-of-the-box functionality, including support for many devices, tools, and programming languages

Unfortunately, NT is optimized more for server environments than high-availability devices that must run 24 hours a day, 7 days a week - without need of an operator or system administrator. With NT, the only way to restart a crashed payphone is to send an engineer to the kiosk to reset it. An expensive proposition.

And, of course, there's always the consideration that an out-of-commission phone could damage BT Payphones' reputation.

Rethinking our options

With these concerns in mind, we began looking at other software platforms. We had three major criteria - reliability, ease of design, and the freedom to create a custom look and feel that would convey BT's brand image. We soon narrowed the choice down to the QNX realtime operating system.

Several factors influenced our final decision:

• QNX has proved to be fault-tolerant and ultra-reliable in hundreds of mission-critical applications, including medical electronics devices and telecommunications systems
• QNX offers an Internet Application Toolkit (IAT) that simplifies the design of custom web browsers and other Internet functions
• QNX's embedded windowing system, the Photon microGUI, allows a design team to brand their product with a unique look and feel

Our engineering team ported the code developed for Windows NT to the QNX RTOS and began to design a working version of the device on our new platform.

On-the-fly upgrades

From the start, QNX made it easier for our team to address key engineering issues. For instance, the QNX RTOS offers the capability to upgrade software - even low-level drivers - remotely. QNX has microkernel architecture, so applications and device drivers remain separate from the kernel and reside in their own memory- protected space. This means that a device operator can send an instruction via the ISDN line that upgrades the software. The OS can execute this instruction for the application being upgraded, without affecting any other application, device driver, or the kernel itself. The software can even be updated while a customer is browsing the web, without stopping delivery of data to the display screen.

In fact, we can upgrade our payphones simultaneously, since each payphone's ISDN line runs directly to a central point, rather than via a local exchange.

What's more, QNX allows rapid and regular updating of advertisements carried on the display screen when the browser is not in use. Each payphone can have its own advertising downloaded to it, making the devices ideal for local advertisers.

Reduced development time

QNX also reduced our development time. First, it provided most of the required software components - GUI, web browser, drivers, and so on - right off the shelf.

As a result, our engineering effort was reduced mostly to supporting the phone's custom hardware: the printer driver; the interface to the smart card that takes payment from consumers; and the electronic components that manage the telephony functions, such as detecting that the handset has been picked up.

The printer driver was taken care of - QNX Software provided that for us. And the development cycle was shortened for the other elements because of QNX's architectural advantages. For instance, under QNX drivers aren't bound to the kernel. Developing a driver is just like developing any application process - it can be debugged, recompiled, and restarted without ever having to rebuild or retest the kernel. As a result, our engineers could focus on writing the interface to the microkernel.

And, because drivers and applications are independent of one another, adding another driver has no impact on those already in service. This is much less complex than the development process for a monolithic kernel OS, such as NT, where every new driver has to be written to the kernel and all potential conflicts with other drivers have to be detected and resolved.

GUI development, too, was simplified. Thanks to QNX's PhAB (Photon Application Builder) development tool, which lets the designer add the GUI as a final layer on top of functionality like web browsers, device drivers, and so on, our engineering team was able to develop the GUI without complicating work on the Multiphone's core functions.

The result of our GUI development is a 12" liquid-crystal display that offers virtually PC-quality graphics. Because it was developed with PhAB, it closely matches the look and feel specified by BT's graphic designers. And, while it doesn't currently offer video streaming or audio, these features are planned for adoption shortly.

Lowered hardware costs

In addition, QNX's architecture is highly modular: engineers can choose the elements that are applicable to the current project and exclude others. This reduces the runtime cost of licensing the OS from QNX; it also reduces the hardware requirement - the QNX version of the Multiphone required substantially less RAM and hard-disk space than the NT version.

Innovative functionality and savings in development time were combined in the solution QNX provided for our user interface hardware needs. First, QNX delivered support for the touchscreen right out of the box. Second, it supplied an almost damage-proof keyboard.

The project team had been considering a rugged keyboard that would be vandal- and tamper-proof - an expensive piece of hardware. QNX gave us another option: a touchscreen keyboard. Users simply touch a section of the screen to make a full QWERTY keyboard pop up. They can then type on the surface of the screen as though they were using a normal keyboard.

Since QNX offered this functionality out of the box, we were not required to invest any development time in implementing it. But it saved the cost of supplying a keyboard as hardware, and the replacement costs associated with it once the payphone is in service.

Business benefits

In addition to the engineering benefits, QNX also offered commercial advantages. As mentioned before, in contrast to Microsoft, QNX doesn't insist that devices carry its branding. While much of the software is QNX-based, it all carries BT's own branding.

The capacity provided by QNX for online upgrading means that the payphone has a longer shelf life than many consumer Internet appliances. As other protocols become common, BT can add these to its version of QNX.

Of course, these upgrades can be delivered remotely without any interruption of service to the consumer.

And because the Multiphone is based on an ISDN protocol that's used across Europe, we have the opportunity to sell the device to telephone service providers outside the UK.

In operation

Over 1000 Multiphone units will be installed in the UK over the next year - in high-traffic areas with a high proportion of potential web and email users. These sites include universities, airports, railway stations, shopping centers, and so on.

For the first time, everyone in the UK will have the opportunity to use online services 24 hours a day - whether or not they have access to a computer at home, school, or in the office.

For more information about BT's Multiphone, visit www.bt.com.