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Putting a Cap on ISDN Line Charges

Article Number: T001
Article Type: Tip
Modified: November 18, 1998

SUMMARY

ISDN can be a very cost-effective access technology to interconnect two or more remote locations. In many locales, though, ISDN call charges are accumulated on a time basis, and therefore any time used in excess of what you may have budgeted for the service may come as a surprise at the end of the month.

Take control with three very useful features available in all Orbitor router products.

MORE INFORMATION

Located in the Remote Site Profile of the Orbitor WAN configuration are three parameters that can be used to control the usage of particular ISDN connections. Since these parameters are configured on a per remote site basis, different caps may be placed on connections to individual locations, taking advantage of the tariff rates between each location.

The three parameters discussed here are Usage Limit, Call Limit, and used in concert with these two, Restart Time. These three are presented below.

Usage Limit

The Usage Limit option defines the maximum ISDN connection time for this remote site.

The time limit is defined in minutes of connection time and is the maximum connection time alotted for this remote site based upon a 24 hour period. The Restart Time option determines when the Orbitor will restart the usage limit timer.

	Default: [unlimited]
	Range: 1 to 2880 minutes or unlimited 

The default of "unlimited" means that there will be no usage limit placed on calls to this remote location. A value of four (4) hours is typical in most ISDN applications, but the value selected should be based strictly upon your alotted budget, and the tariffs applied to ISDN calls in your location.

Call Limit

The Call Limit option defines the maximum number of ISDN connections allowed to this remote site over the defined 24-hour period. The Restart Time option determines when the Orbitor will clear the call limit.

	Default: [unlimited]
	Range: 1 to 86400 calls or unlimited

The default of "unlimited" means that there will be no connection limit placed on calls to this remote site. A value of 50 may be appropriate, but chose the value of this parameter based upon the call connection charges applied to ISDN calls in your location.

Restart Time

The Restart Time option defines the time of day that the call limit and usage limit timers will start recounting. This parameter defines the start and end of the 24-hour period used above.

	Default: [07:00]

Normally, the value of this parameter will reflect the start of your day, or a time that will be just prior to the start of your day.

Basic Operations

When configured to place a cap on ISDN usage, the Orbitor will continue to monitor the call activity to the remote site. When either of the usage cap limits have been exceeded, the Orbitor will prevent further calls to this location until the next "Restart Time".

Although these features are intended to prevent unnecessary ISDN call charges, they will cause what can be perceived as service disruptions when the limits have been exceeded. When the limits are exceeded, the Orbitor will preclude further connections to that remote location for the remainder of the 24-hour period.

CONSIDERATIONS

The use of these parameters is recommended for most ISDN applications. In those regions that do not charge for ISDN call access, of course, these parameters may be ignored and left in their "unlimited" state.

REFERENCES

Please consult the Orbitor Reference Manual for details regarding the use of these features.§

Copyright © 1998 Develcon Electronics Ltd.  All Rights Reserved.