Linux Information

This section of our technical library presents information and documentation relating to the Linux operating system especially as it relates to the telecommunications and Linux CRM Software marketplace. Since the Company's inception in 1978, DSC has specialized in the development of software productivity tools, call center applications, computer telephony integration software, and PC based phone systems. These products have been developed to run on a wide variety of computer systems and have been tested and operational on LINUX servers and systems. The following are articles and information regarding Linux and its applications in the telecom and business environments.

September 2000 issue of Voice2000, a supplement to Business Communications Review, pp. 20–23
by Stephen Coates, an independent telecommunications consultant and author of Computer Telephony Integration: Integrating Enterprise Communications.

Pick up almost any computer magazine and you'll find something on Linux. It is enjoying increasing uptake as a growing number of commercial products are able to work on it and it is nibling at Microsoft's Windows in the corporate world (see "Linux In The Corporate Network?" in BCR, January 2000). Linux, which can be used for a wide variety of applications, is mostly used with Internet servers, but it has recently begun to make its debut within the domain of telephony, both in America and even more so in Europe.

When the first version of what was to become Linux was developed by Linus Torvalds in 1991, it was released under the GNU (a recursive acronym for GNU's Not Unix) Project, the core of which is the GNU Public Licence (GPL). Under GPL, software and source code are supplied free, but any new software developed from or using software subject to GPL is itself subject to GPL.

This open source environment has resulted in tens of thousands of programmers contributing code, modules and other extensions to Linux, and applications written specifically for it. It has also led to a perception that Linux is the last bastion of the "propeller-heads" who eschew shrink-wrapped software packages and long for the challenge of cutting operating-system-level code

To be sure, Linux has the scope to develop capabilities that the alternatives cannot. The operating system is modular, comprising a very compact kernel to which modules offering the required functionality can be loaded into memory only if and when required. Linux can thus work very well with as little as 8 Mbytes of RAM.

Another strength of Linux's Unix heritage is its stability. Linux machines have a reputation of being able to operate for months, even years without crashing or otherwise failing. And although viruses for Linux exist, there are very few of them, at least for now.

Linux for Telephony

The world of telephony comprises a number of different system categories, each with its own considerations and parameters. At the core of any telephony environment are switches—PBXs and central office exchanges—typically modular in construction, with the largest comprising several racks of interface circuits connected by time-division buses to one or more time-division switches, controlled by a CPU. Although highly configurable and able to be controlled through a number of interfaces, the hardware and software is sold as an indivisible package, with essentially no facilities for users to perform their own software development.

Switch Operating Systems: The paramount consideration of a switch's operating system is reliability. It must perform one key function— switching calls—and to do this for years without interruption. While most switches use proprietary operating systems, there are exceptions. For example, Selta (Tortoreto, Italy) and Salix (bought recently by Tellabs) both use the pSOS operating system for their SAE 3000 PBX and ETX5000 exchange, respectively. pSOS was developed by ISI Inc, itself recently acquired by Mindriver.

ACD manufacturer Rockwell uses Windows NT for its smaller Transcend ACD and OS/9 for the larger Spectrum system. Al Hukle, Rockwell's manager of Electronic Marketing, said that OS/9, a product of Microware Systems, was selected because of its "exceptional ability to handle multiple real-time tasks simultaneously and its reliability when used in critical applications." Other operating systems used by PBXs include Newcleus and p-Source (LG, Korea), Vxworks (Mitel, Kanata, Ont.) and IRMX (Matra, France).

But Linux is starting to make its presence felt. EOn Communications (formerly BCS Technologies, Memphis, TN) has been using Linux as the operating system of its DSP1000 ACD since 1997. Gary Spears, eOn's director of the International Division said that the company chose Linux "because it gave us access to the latest technology. There are many more people developing drivers and building applications for Linux than for any other operating system that will suit our needs. Linux has a fantastic real-time kernel and a massive driver library that is being expanded by programmers worldwide on a continual basis."

Some other manufacturers are more than interested. Teltronics (Sarasota, FL) has chosen Linux as the operating system for the new central processor it is developing for its Vision PBX. According to Pete Tuckerman, Teltronics' vice president of Product Management, Linux's advantages are cost, stability and, in particular, its open source, which Tuckerman said "is critical for a PBX company. Open source allows us to tune the operating system to our needs. There is also the development environment in which there are many new, powerful application development tools and many bright people constantly improving Linux and adding new capabilities."

Other PBX manufacturers who are planning to use Linux include Teldev (Viernheim, Germany) 2N (Praha Czech Republic) for their respective MIX Pegasus and Ateus-Omega PBXs later this year.

PC and LAN-based Telephony: Another two categories of telephone systems are PC-based telephone systems, which use the standard PC architecture for the main chassis, and LAN-based telephone systems, which are sometimes referred to as UnPBXs. There are about 70 such systems commercially available in various parts of the world, the vast majority of which use Windows NT; far behind are other operating systems, including VxWorks, pSOS, DR-DOS and OS/2. While none of the UnPBXs currently use Linux, the following companies have announced their intention to do so:

Add-Ons—IVR and Voice Mail: Add-ons such as interactive voice response (IVR) systems, voice mail systems and audio call recording systems (aka call logging systems) are also beginning to be developed with Linux. These systems typically comprise a number of voice interface circuits to the switch and a CPU, and IVR systems usually also have a LAN interface.

In contrast to PBXs and exchanges, most IVRs, voice mail systems and call loggers are manufactured by smaller companies using readily available components, the most significant being circuit cards, which are available from 30 or so suppliers. The circuit cards come with drivers, which are written for specific operating systems. Among the vendors making Linux drivers are:

The preferred operating system for small to medium-sized IVR systems is Windows NT, although Unix is the preferred choice for larger, telco-grade systems. The only use of Linux within this category was for some of InterVoiceBrite's IVR products for the telco environment.

CTI and Call Center Systems: Call center/ desktop CTI systems, predictive dialers and products which support collaborative Internet browsing typically have a client/server architecture. Desktop support is most often Windows (although there are MacIntosh and Unix desktops as well) and MacIntosh and Windows NT is becoming dominant for servers.

At first glance, if Linux was to make major inroads into the telephony, this is where it would start. A survey conducted by the Internet Operating System Counter in April 1999 found Linux to be the most popular operating system, being used by 31 percent of the ISPs polled. And a recent survey by IDC found Linux to be a major competitor to Windows and Unix for server applications, with 13 percent of companies polled using Linux, compared to less than one percent in 1997.

In fact, however, progress is still slow, although it is for these applications that Linux is enjoying the greatest, albeit modest, uptake.

Conclusion

From a developer's standpoint, there are three commonly cited "cons" which hold back the Linux market:

• The cost to acquire/develop staff skills while maintaining non-Linux ("legacy") systems/products already in place.
• The multiplicity of versions of Linux with no single source of worldwide support for any of them.
• The lack of suitable development tools.