The ISDN Diva Server Advantage

Eicon Networks' DIVA Server adapters are active ISDN adapters, based on a high performance RISC processor and a number of DSPs per board. While the RISC processor handles protocol processing tasks for the whole board, each DSP6 chip is dedicated to one active call where it does the low-level processing of the analogue signals. The DSP is able to switch in different tasks depending on whether it is doing VoIP, V.90 (56k) modem emulation, or talking to a GSM mobile phone. With this architecture it is possible to offload all of the communications processing from the host PC onto the DIVA Server, leaving the main CPU to get on with its main task.

The DIVA Server family is scaleable and interchangeable: they are all based on the same architecture and use the same software. Any combination of DIVA Server BRI, DIVA Server 4BRI and DIVA Server PRI adapters can be used together, depending on the number of BRI or PRI interfaces required for the specific application. Software is loaded onto the board at the time the host PC is loaded, so this means that the software can easily be changed or upgraded without reinvesting in hardware.

The current DIVA Server family looks like this (all are PCI interface adapters):
• DIVA Server BRI - Single BRI (2 channels) server adapter: ISDN, Fax, GSM and V.90 modem
• DIVA Server 4BRI - Four BRI interfaces (8 channels): ISDN, Fax, GSM and V.90 modem
• DIVA Server PRI 9M - PRI adapter for fractional primary rate, up to 9 channels (30 digital channels, but up to 9 can support GSM, Fax and modem sessions).
• DIVA Server PRI 30M - PRI adapter for 30 channel primary rate: ISDN, Fax, GSM and V.90 modem

The DIVA Server Voice family support all the functions of the standard DIVA Server products but also support H.323-compatible Voice over IP communications:
• DIVA Server Voice 4BRI - Four BRI interfaces (8 channels): VoIP, ISDN, Fax, GSM and V.90 modem
• DIVA Server Voice PRI - PRI adapter for 30 channel primary rate: VoIP, ISDN, Fax, GSM and V.90 modem

An important feature of the DIVA Server products, is that a number of different functions are rolled into the same platform:
• Remote access for ISDN, V.90 modem and GSM.
• Full fax modem features: supports G3 mode (to 14400bps) and G4 (64kbps).
• CAPI interface: open interface for ISDN applications (voice, fax, data).
• Voice over IP gateway (DIVA Server Voice cards only)

Many products from other companies are split into separate ranges: e.g. one range of fax adapters and another for RAS adapters, or one range of CAPI adapters, and another range of non-CAPI adapters. With DIVA Server, there is a common platform, so an adapter bought for a fax server can later support other applications without hardware change. Similarly, when the fax server comes to the end of its life, the DIVA Server board can be recycled for other purposes, e.g. WAP server.


Unified messaging and Fax Gateway
Today, the best way to implement a unified messaging system is using a server based solution. There are many types of router box you can get to connect to a network, but a unified messaging software package relies on an open API such as CAPI in order to communicate with the communications hardware. This is most efficiently handled when application and hardware exist in the same host PC. All the DIVA Server adapters support CAPI, so the unified messaging and fax applications always see the same interface, just with different numbers of channels available.

Unified messaging will become a much more prevalent Internet-based application in the future, but reliable, flexible services do not exist today. Also, the Internet based solution is often compromised today by the fact that most Internet users cannot be permanently connected to the Internet (for reasons of tariffing). This means that instant notification of messages is not available for most users today. With a server-based, private solution you have much more flexibility with something that exists today.

Where VoIP will also be an application area, it makes sense for voice applications and VoIP to share the same server. Because ISDN has voice built-in as a standard feature, it is very easy to implement a digital voice application either by using a unified messaging product, or by developing a custom application using the CAPI interface. This could be as simple as an electronic answering machine, or it could be a voice-controlled application for automated fax retrieval (fax back).

A VoIP gateway also needs a physical interface to the outside world (in this case via ISDN), and also has a digital side. Two areas where unified messaging and VoIP can work together are voicemail and fax over IP (FoIP). If a user is not in the office when a call comes in via the VoIP system, it makes sense to divert to voicemail, and this is an area where VoIP needs to co-operate with other digital voice systems. In the case of FoIP, it makes sense to collapse fax service and VoIP into the same gateway, as this offers the same economy in call costs as for standard voice calls. If a fax call would normally be sent over the public phone network (incurring timed call charges, perhaps at International call rates), it can be digitised in the VoIP gateway and sent at no extra charge over the data backbone to another office.


Remote Access and WAP/SMS
Remote Access is still a popular application for server-based ISDN. While some companies prefer to outsource this job to an ISP, those with privately owned RAS facilities can enjoy more security and more uptime. A key component to making it possible for workers to work from anywhere at any time is to make it easy to access the facilities. With ISDN, access is fast (fast dialup, 64kbps full duplex throughput) and it's a dedicated network: you don't have to share your RAS server with any other ISP customers.

WAP and SMS are growing in importance for instant messaging and interactive data retrieval for mobile users. Server-based ISDN offers a platform for building bespoke WAP and SMS messaging systems, and there are also a number of evolving WAP server applications for Windows and Linux.