Configure maximum call settings


  • Telephony > Plugin > All permission

The maximum call settings apply to both external trunk and phone trunk settings. You can limit or expand the maximum number of combined active inbound and outbound calls that are allowed on an external trunk or on a phone trunk.

On an external trunk, the Max Calls setting is a per trunk setting. Setting Max Calls to 0 (zero) will configure the trunk to accept an unlimited number of calls.

Note: If you are using a BYOC Premises and set Max Calls to 0 (zero), be sure to take into account the concurrent call capacity for your Edge devices. Setting the Max Calls to 0 (zero) does not increase the Edge’s concurrent call capacity. For more information, see Concurrent call capacity for Edge models

By default, a trunk returns a 503 Service Unavailable reason code if the Max Call threshold is exceeded. However, when you configure an external trunk, you can use the Max Calls Reason Code setting to specify a custom SIP response code for this condition. You can use a SIP response code in the 4xx, 5xx, or 6xx range. This allows you to configure a response code, such as 486 Busy Here, to more accurately indicate that the Max Call threshold is exceeded. 

Note: The WebRTC phone trunk does not have a Max Calls setting.

For more information on external trunk settings, see the External trunk settings reference.

Configure the maximum call settings

  1. Click Admin.
  2. Under Telephony, click Trunks.
  3. Click the appropriate tab: External Trunks or Phone Trunks.
  4. From the list, select the trunk you want to configure.
  5. Under the External Trunk Configuration or the Connection Configuration section, click General.
  6. In the Max Calls box, enter the maximum number of combined inbound and outbound active calls.
  7. In the Max Call Rate box, enter the average number of calls permitted per second. 
  8. In the Max Dial Timeout box, enter the maximum delay allowed before an outgoing call attempt is aborted.
  9. In the Max Call Reason Code box, enter the SIP response code that you want the trunk to return when Max Call threshold is exceeded
  10. Click Save External Trunk or Save Phone Trunk.