Limit Outbound Call Frequency of an Extension

Capping how quickly an extension can dial out is a simple but effective defense against toll fraud. If an account is ever compromised, a frequency limit stops the attacker from placing a flood of calls before you notice, keeping the financial damage small. Apply a rule to any extension you want to protect.

Apply a restriction rule

1. Sign in to the PBX (Private Branch Exchange) web portal and open Extension and Trunk > Extension, then open the extension you want to protect for editing.

2. Switch to the Security tab.

3. Find the Call Restrictions section and open the Outbound Call Frequency Restriction drop-down. Choose one or more rules to enforce on this extension.

   Note

   Cloud Voice ships with a built-in rule, Default_Ext_Outbound Call Frequency, that allows an extension to place at most 5 outbound calls per second. You can also define your own limits, see Add an ‘Outbound Call Frequency Restriction’ Rule.

4. Click Save, then Apply.

What happens when the limit is reached

Once an extension goes over its allowed call frequency, the system responds in a few ways:

Caution

Exceeding the limit does more than throttle the next call: Cloud Voice fully disables outbound calling for that extension and keeps it blocked. The extension cannot dial out again until you clear the block by hand (see Lift the block manually), so set limits that fit normal call volume and watch for the exceeded-frequency notification.

• The extension can no longer place outbound calls, even when it is included in your outbound routes.

  Note

  Emergency calls such as 911 are never blocked by this restriction.

• A warning icon appears beside the extension in the extension list.

• Cloud Voice sends an alert to the recipients configured for the Outbound Call Frequency Exceeded event.

Lift the block manually

To restore outbound calling for a blocked extension, click the edit icon next to it, go to the Security tab, and clear the Disable Outbound Calls checkbox in the Call Restrictions section.