11.1.6. Switchover in Emergency Mode 
When a HG 3575/virtual HG 3575 discovers an interruption of the signaling
connection to the central control unit, it reports this event to the
allocated survivability unit.
Emergency mode, that is, when access point/OpenScape 4000 SoftGate
is controlled by a survivability unit, is the one escalation level higher
than signaling survivability. If signaling survivability is configured
when the connection is lost, signaling survivability first attempts to
control the access points/OpenScape 4000 SoftGates via modem. Emergency
mode is initiated if this fails (for example, because central control
unit is not available).
The survivability unit uses preconfigured rules to decide whether
it should take over access point/OpenScape 4000 SoftGate control or not.
- Each access point/OpenScape 4000 SoftGate is assigned a weight.
- If the total weight of all access points/OpenScape 4000 SoftGates in an emergency group that has lost its connection to the central control unit is greater than the limit specified, the survivability unit assumes control of all access points/OpenScape 4000 SoftGates assigned to this group
- However, access points/OpenScape 4000 SoftGates can also be configured so that they can always be individually controlled by the survivability unit regardless of their weighting.
- In addition, you can switch control of
- individual access points/OpenScape 4000 SoftGates
- all access points/OpenScape 4000 SoftGates in an emergency group
- all access points/OpenScape 4000 SoftGates in all emergency groups in a survivability unit or
- all access points/OpenScape 4000 SoftGates in the entire OpenScape 4000 system
to the assigned survivability unit(s) at any time.The survivability unit takes over control of the access point/OpenScape 4000 SoftGate by instructing the HG 3575/virtual HG 3575 to initiate a restart and then start up with the survivability unit. The HG 3575/virtual HG 3575 restart triggers a restart in all peripheral boards on the access point/OpenScape 4000 SoftGate. - All calls are cleared down.
- Features with active logon, e.g. mobile subscribers (PIN, mobile HFA), are logged off.
- Features that can be configured by the user, such as key layout for (name keys, DSS keys), forwarding key, reminder key, etc., are set up in the state that they were in when the data was incorporated from the host system (see also Section 1.8, “Configuration Data”).