8.12.2.4. Restrictions 
- This feature is only active for voice calls.
- The feature is not supported for DSS1 phones (S0), attendant consoles or analog voice terminals connected to a T/R adapter!
- ONS group for CHESE (chief secretary group) members is not supported.
- ONS group members cannot be members of call pickup groups.
- ONS group members must not be configured as night stations.
- ONS group members must not be configured as ACD agents.
- If the master of an ONS group is a SIP subscriber, the secondary members cannot be HFA subscribers.
- MLPP, Emergency Override and emergency disconnect is not supported from and to ONS group members.