11.8.2. Restrictions 
The feature has the following restrictions:
- GNS destinations (Analog or Digital) within OpenScape 4000 can only be local.
- If the TNS destination is a single device (analog or digital)there is no call waiting terminating feature (camp on) .Therefore a master hunt group should be configured to allow camp on of more than 1 night service call
- If the TNS destination is busy the system will try after a time out a new attempt to connect i.e, it will be polled. This could cause additional traffic on a network
- Cot parameters FWDN and FNAN must be set in all transit and centralised attendant nodes to enable the feature to work