8.12.2.3. Notes on Configuration 
- Subscribers can not be added to OSN groups after they are configured. In this case regenerate,delete and re-add the ONS group with the new subscriber information.
- All members of an ONS group (master and slave - subscribers B1, B2 and B3) are to be configured in the same node.
- Subscribers of an ONS-group must be in the same ITR-group.
- The parallel ringing station group is configured via AMO AUN with parameter TYPE=ONS.
- Internal ONS members are assigned by the AMO AUN as group members. The ONS group consists of exactly one ONS master (who has the AMO SDAT parameter PARARNGM) and secondary members (who have the AMO SDAT parameter PARARNGS).
- The external ONS member number is assigned by the parameter REMAC. For this external member a virtual secondary device has to be added as ONS member. This virtual secondary device is configured via AMO SCSU with DVCFIG=AUXDIGI and INS=ACLSTN and via AMO SDAT parameter PARARNGS.
- The ONS master must have a PIN activated with the following AMO PERSI COPIN values: PINDUR=PERM (permanent), PARARNGM=YES (pararing master), TRANSFER=ALL (tranfer all key contents and cos), COSHOME=YES, DISPRSTN=NO (no display of remote station) and IDHOME=NO. Outgoing trunks to the central office or to the expression server must have the COT parameter VNCO so that the permanent PIN is considered for outgoing calls from an ONS member.
- The AMO AUN parameter SMPF (search mobile phone first) indicates
for a basic call to an ONS group the following:
SMPF=YES: The mobile phone is called first before the internal ONS members are called (waiting a time period specified by the AMO CTIME parameter SMPFTIME). If an external station (REMAC) is used in an ONS group, the parameter SMPF is fixed to YES and cannot be changed.SMPF=NO: The internal ONS members are also called immediately.
IMPORTANT:
SMPF is not considered e.g. for a consultation call to the ONS group or if call waiting is active for this call. - The AMO AUN parameter ONSSNS indicates if the number of an ONS secondary member should be suppressed or not.
- The AMO AUN parameter PUSECOND indicates if the pickup of
a second call to the ONS group is enabled or not. This AMO parameter
is relevant for an ONS group where the internal members are only anates.
For an ONS group call waiting can be (de)activated via key at the device.
In addition to the PUSECOND parameter: If there is an ONS group with only anate members (and maybe a virtual secondary member and a REMAC) and the feature call waiting should be active for this ONS group then it is recommended to add a virtual ONS master to this ONS group. Only then the call waiting feature is supported. This virtual ONS master must not have the AMO COSSU COS parameter MB (mailbox) assigned and must not have a MB key assigned via AMO TAPRO. This is necessary to ensure that a callback to this anate ONS group is handled according to CCNR (call completion no reply) and not according to the mailbox function (where the mailbox key doesn't exist).