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If the Session option Enable Dialing Restrictions is selected for a port group, then the modem will only dial numbers that are permitted by the Dialing Restrictions that are configured for the port group.

 

 

Configuring Dialing Restrictions

 

Open the Properties Window for the port group.  Click the Dialing Restrictions tab.  In Default Action, specify the action to take if a number being dialed does not match any dialing rule.  Select Enable Dialing Restrictions in the Session Options for the port group.

 

To create a dialing rule, click Add; or use the Ins key and then type in a phone number pattern.  All printable characters will be allowed, but the only characters that will be used in dialed number matching are:

 

 

To edit a Phone Number Pattern, double-click the pattern; or click the pattern once and then click Edit.

 

Double-click to change a Type between Allow and Block.

 

To change the position of a dialing rule, click it and drag it to another location in the list; or click the rule and use the up/down arrows to move it in the list.

 

To remove a dialing rule, click it to select it.  Then click Remove, or use the Del key.

 

The Dialing Restrictions window

 

 

How the Dialing Rules are Used

 

If dialing rules are enabled, then they will be used when a client software application issues a modem dialing command. The telephone number being used in the modem dialing command will be normalized by removing all but a small set of characters for the purpose of matching the phone number with the rule.  Specifically, all but the following characters will be removed prior to matching:  0123456789ABCDabcd,#*.

 

Before a rule is processed, the number pattern will be normalized like the dial command number above, except '?' and '\' (backslash) are allowed to accommodate wildcard matching.  Specifically, all but the following characters will be removed prior to matching:  0123456789ABCDabcd,#*.?\

 

The asterisk dialing digit (*) overlaps with the use of the asterisk as a wildcard.  To create a pattern that matches an asterisk, it must be preceded with a backslash (\).  For example, to match 800 numbers that begin with "*72", use the following pattern:  \*72,1800*

 

For each dialing rule, the normalized dial command number will be compared to the normalized pattern.  Matches are case-insensitive.  If there is a match, then the associated Allow or Block action will be taken, and no more rules will be processed.  If all rules are processed and there have been no matches, then the Default Action Allow or Block will be the result.

 

The setting for Default Action will establish the basic approach to dialing restrictions.  Using the default of Block means that the dialing rules must cover all numbers that should be allowed.  Using this approach, it is easy to prevent calls to toll numbers and ISP access numbers, without knowing each number.  Make sure to update the dialing rules when new numbers must be allowed.

 

Using the default of Allow means that the dialing rules must cover all numbers that should be blocked.  Using this approach, dialing rules may be devised that will prevent all of the calls that should be blocked.  Consider all of the number patterns that will be applied to international, long distance, intrastate toll exchanges, caller-paid area codes, 911, 411, and ISP access numbers.

 

Example 1:  Restrict to One Block of Numbers Plus USA Toll-free Numbers

 

Example 2:  Restrict to Local and USA Toll-free Numbers

 

If the Dialing Restrictions are not working as expected, then view the Event Log to see exactly what calls are passing the dialing rules.  When configuring modem applications on client computers, the numbers being dialed must work for the server computer's location and telephone service, which may differ from the client computer.

 

If the telephone system being used by the modem requires an access number (e.g., 9), then it must be included in the dialing rules.  Changes in Dialing Restrictions will not affect current sessions. Dialing Restrictions for all port groups may be enabled and disabled at once using Disable dialing restrictions and call logging in Server Options.

 

 

 

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