5.1.5. Physical and Virtual Node 
The physical node defines the PABX, virtual nodes define groups of
subscribers with the same numbering plan. Every subscriber and Attendant
console must be assigned to a virtual node (by. AMO SDAT). Virtual nodes
are managed with the AMO KNDEF. The numbering plan data for ISDN E.164/
PNP number plans and for the OpenScape 4000 implicit numbering plan can
be defined for every node .Within a physical node at least one virtual
node must be defined. However, this can also extend over several physical
nodes, or several virtual nodes be within the same physical node.
A virtual node must be defined as a default node. The default node
is used to enable a node number for phone numbers, e.g. attendant and
attendant group code numbers which are not explicitly assigned to a virtual
node..
The introduction of virtual nodes became necessary by the introduction
of two new features:
- IPDA:
Due to The subscribers of access points being assigned to different locations If e.g. an Access Point is in Berlin, a different one in Munich, then the participants in Munich shall be accessed under a Munich C.O. phone number and in Berlin under a Berlin C.O number, This is achieved by assigning the participants to two virtual nodes ,these both lie on the same physical node but have different E.164 numbering plan data.
- USA EPNP:
U.S. American PABX's often have not one but several main office phone numbers.This means that the public number plan in the USA can often provide no more sufficient free direct dial numbers ranges in the required size . E.g. a business needs 1800 Direct Dial numbers, perhaps it must buy 2 3-digit direct dialling areas at 1000 numbers each and has therefore two E.164 Local destination codes. Moving a station in a private network retaining the phone number (E.164/PNP/OpenScape 4000 Numbering plan)has to be possible.The normal case is: A physical node has a virtual node.Virtual nodes are, identified by the virtual node number, physical nodes by the physical node number.Virtual nodes have a virtual node code for the OpenScape 4000 numbering plan and /or E.164 or PNP codes. physical nodes have a physical node code.The following pictures show the normal configuration and the application case mentioned:
Figure 8. Normal configuration for 2 PABX's
Figure 9. IPDA Configuration
Normal configuration after a move of stn 4716 taking with it the phone number and the E.164 number in the implicit OpenScape 4000 number plan ( open numbering)3 virtual nodes exist on a physical node.Figure 10. Normal configuration after a move of a station
The virtual node 5-5-1 has extended itself into the physical node 1-1-2 and is identicaly configured on both physical nodes.