11.1.6.2.1. Feature Description 
Calls waiting longer are diverted after time to another Attendant
group. This behavior is administerable. Every Attendant group (VFGR)
has an overflow aim of its own. The overflow is active then if another
Attendant group than overflow aim is registered.
The priority level of calls with a low priority level is increased
to the highest priority level (priority level 2) after timeout. Priority
level 1 is reserved for Emergency calls only and can not be reached by
Priority Upgrade.