5.21.1.3. US EPNP 
One special case of a numbering plan is the plan formerly used in
U.S. systems (R6.6), EPNP (Enhanced Private Numbering Plan). In the process,
a PNP numbering plan that works without an exit code and without prefixes
is configured. The number thus complies with the following scheme:
|
Phone number:
|
Exit +
|
Prefix +
|
Code(s) +
|
Direct in dial
|
||
|
L2 Code
|
L1 Code
|
Loc Code
|
||||
|
e.g.
|
99
|
88
|
777
|
4711 (Level 2 STNO)
|
||
|
|
88
|
777
|
4711 (Level 1 STNO)
|
|||
|
777
|
4711 (Local STNO)
|
|||||
Abbreviations: STNO=Station, i.e. phone number
In special cases, exit codes may also exist.
A normal PNP for comparison:
|
Phone number:
|
Exit +
|
Prefix +
|
Code(s) +
|
Direct in dial
|
||
|
L2 Code
|
L1 Code
|
Loc Code
|
||||
|
e.g.
|
9
|
11
|
99
|
88
|
777
|
4711 (Level 2 STNO)
|
|
9
|
1
|
|
88
|
777
|
4711 (Level 1 STNO)
|
|
|
9
|
777
|
4711 (Local STNO)
|
||||
A typical EPNP, however, only consists of a three-digit local code
(no L1 and L2 codes) and a six-digit internal number. The signaling takes
place in explicit format with NPI= PRIVATE and TON=LOCAL.
Since the number that can be dialed (i.e. the implicit number) has
no exit and no prefixes, it is thus more similar to a number of the OpenScape
4000-implicit numbering plan. The consequence is that no unique, explicit
number can be extracted from the implicit number. The configuration is
thus a mixed form of the explicit numbering plan and cross codes (for
an example, see below).