The system can be set to check at regular intervals if the device is still online. If the device does not answer within the configured period of time (in ms-milliseconds), it is considered offline for future calls. This is done via qualify option. The default time is 2000ms(2 sec).

To set the qualify time:

1. Login to the system administration.

2. Click on corresponding icon to edit Trunk.

3. Under the 'General' group there is a 'Qualify' option.