The Internet Connect Timeout option

Configure->InternetConfig->LineUp

This select box allows you to set the length of time, during which no data passes to or from the Internet, before the Server drops the connection:

At all other times the connection will be dropped within a few seconds.

The advantage of setting a short time, e.g. 2 minutes, is that it can make an appreciable difference to the on-line time, and therefore to telephony costs.  The disadvantage is that, whilst users are browsing web sites, the System may drop the connection and have to re-dial more often.

The default setting for this field is 5 minutes.