Open Architecture Computer Telephony Servers and Tools

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CALLHANDLER SCALEABILITY - BASIC Versus PRIMARY RATE CONNECTIONS WITH TELEPHONY CARD CONFIGURATIONS

A Common Interface. The CallHandler Computer System uses Telephony cards from Aculab which are assembled into a Rack-Mount or Tower type PC Chassis. CallHandler also incorporates other PC cards for LAN/WAN connectivity etc., and is controlled by Windows NT. Its important to understand how the Aculab Telephony cards are configured, as this is the core building block for all of the CallHandler solutions.
The Aculab Telephony Cards have a consistent level of functionality built in, and the only variation is the type and number of lines they can support. The cards have a common 'Prosody' Module which incorporates a wide range of functionality. It is this Prosody module that the CallHandler Software interfaces to, which means that no matter what the size of your system you get consistent availability of application functionality - e.g. FAX, Voice Mail, Conferencing etc. You can start small, with limited functionality and lines, and grow the system later by activating other on-board modules which are already on the card(s). In all cases, your original application can be run with no change whether you have a 10 or 10,000 line system.

CallHandler only operates on Digital ISDN Telephone Lines. It does not support analogue input. e.g. 56K modem type input. There are two types of digital ISDN lines. viz:

BASIC Rate - Two lines per connection point (64KB each line)
Primary Rate - Known as E1 or T1 which supports 30 and 23 lines respectively (64KB each line). Can be used with a limited number of live lines - e.g. 10 of the 30 are active, 20 dormant

BASIC Rate versus Primary Rate. In order to understand how the hardware is configured for different types of input it is important to be clear on the differences between these. The differences from a user perspective are very simple. Each has a unique physical connection (on the wall), and each carries a different number of lines. BASIC Rate has two 64KB lines per connection, and Primary Rate (E1) has 30 lines per connection. BASIC Rate tends to be used in domestic applications, such as Internet access from peoples homes. Primary Rate tends to be used by Corporates; an example use of a Primary Rate connection is a company with a line hungry switch board, another example is an Internet Service Provider. The number of lines available is the most important differentiator between the standards.
The deciding factor when choosing BASIC Rate over Primary rate is cost related - e.g. the cost of line rental and the cost per line of the CallHandler System. You could, for example, have 15 BASIC Rate sockets installed to give a 30 line capability, but this would not be as cost effective as using a single Primary Rate ISDN port.

Varying Board Connectivity - Constant Functionality
The diagrams below show how the Aculab Telephony cards are configured. They present a consistent set of hardware functionality, for varying connectivity configurations.

BASIC Rate Connectivity - 8 or 16 lines per card

8 Line BASIC Rate ISDN

16 Line BASIC Rate ISDN

Primary Rate Connectivity - 30, 60, 90 or 120 lines per card. (6 cards max. per chassis)

30 Line Primary Rate ISDN

120 Line Primary Rate ISDN

The minimum configuration for CallHandler is 8 lines using 4 off BASIC Rate ISDN digital connections. CallHandler is 'infinitely' scalable, so there is an option to start small and expand the system as your business grows - both in terms of number of lines, and system functionality.

Go to this section for an explanation of when to use digital rather than analogue lines. It uses basic computer telephony system configurations, starting with a simple fax system and building up to a comprehensive voice based CallHandler system. Fax is used in the example because it is simple to understand, but this represents only a fraction of the capability of the CallHandler system.

Chelston Call Systems Ltd.
49 Dove Park, Chorleywood, Hertfordshire, England, WD3 5NY
Tel: 01923 286501 - Fax: 01923 286498
Located just north of Heathrow Airport, London
Email: Mike Quelch at info@Chelston.co.uk