5.2.1. Feature Description 
This feature provides an additional possibility to reach an alternate
destination in case of voice calls, if the called subscriber/ personal
attendant is in an out_of_service (OOS) situation.
The feature performs a new kind of alternate routing mechanism, using
new predefined alternate routing destination numbers, which can be subscriber
individual or source group related. In some cases (see below), new authorizations
will be validated.
In total, 6 different OOS scenarios of the called subscriber/ personal
attendant will be handled.
- The called subscriber / personal attendant is OOS because of a device/board error.
(no additional authorization necessary)
- The called subscriber / personal attendant is OOS because switched off by AMO.
(authorization necessary for doing alternate routing when manual switched off by AMO)
- The accesspoint (AP) of the called subscriber is in an AccessPoint Emergency (APE)
situation in
relation to the AP of the calling device.
(no additional authorization necessary)
- The called HFA IP phone is in OOS and has registered at OpenScape Business/HiPath
3000 because
of IP errors.
(authorization necessary for move logon from OpenScape 4000 to OpenScape Business/HiPath 3000)
- The called HFA IP phone is OOS because of a system failure and has been moved to /
has logged on
to another OpenScape 4000 node.
(authorization necessary for move logon from OpenScape 4000 to another OpenScape 4000 node)
- For HFA IP subscribers, which have de-registered and are newly registered somewhere else, a TSC setup from a XPRESSION server for indication of a voice message, will be alternate routed to that switch, where the HFA IP subscriber is registered actually.
Normally, alternate routing will be done only once for a call. In case
of an alternate routing because of APE, it might be necessary to execute
another alternate routing again for on of the other 3 mentioned OOS scenarios.
The reason why is, that in kind of APE, in the AP of the calling device,
it can not be verified for sure, whether the called subscriber in the
target AP is in a seizable condition.
Because of this consideration, it is possible to administer two types
of alternate routing destination numbers (OOS and APE) for a subscriber
or a whole source group with different alternate destinations.