8.12.2.1. General Notes 
- Up to 2000 parallel ring groups (ONS group or a call pickup group) are supported within one OpenScape 4000 node.
- The maximum number of ONS members is 3 (master and two slaves).
- Anates, digites, HFA subscribers, SIP subscribers and virtual secondary
devices are considered as ONS members (master and/or slave). A virtual
ONS master or a REMAC number doesn't count as ONS member
in this respect.
If the master/slave of an ONS group is a SIP subscriber please refer to Section 86.2.5, "ONS Groups with SIP Subscriber as Master/Slave".
- As slave (instead of B2 or B3) one GSM mobile phone or another external terminal may be in an external GSM network with the special ringing function "search mobile phone first" (SMPF).
- There is no busy signalization of the ONS master number, if the external subscriber has taken a call.
- One ONS member can call another ONS member of the same group (ONS internal call).
- Last number redial, saved number redial, speed dialing, namekeys, direct station select keys and reminders are available for each ONS device separately.
- For incoming calls the ONS master extension number B is equal B1.
The features call waiting, call forwarding (CFW), do not disturb (DND), message waiting indication (MWI), callback and call logs are ONS group features.
- Outgoing calls are always initiated with the number, COS and LCOS of the
master extension.
Same COS, same ITR group, same WABE group and same COSX group. This is ensured by using the Permanent PIN feature. The pin of the master device is automatically activated on all slave devices by starting up the phone or by configuring a new ONS group.The permanent PIN cannot be modified by the ONS device; only a short PIN, valid for only one call can be activated.
IMPORTANT:
PIN for SIP phones is not implemented yet, therefore activation of master PIN is not possible on SIP phone slaves.