Expert Documentation

DID numbers can:
- contain up to 8 digits.
- use the number recovery operation described below.
3.16.1.1.1 NUMBER RECOVERY
Description
When, in an existing installation, a new range of DID numbers needs to be added, and the new
sequence assigned by the public exchange overlaps the existing range, the installer can make
use of the "DID with more than 4 digits" operation.
Example:
Consider an existing system with the DID numbers (XX = any possible "intercity prefix",
"intercity code" and "recall prefix" – these can vary from country to country):
- XX 1 41 23 40 10 to XX 1 41 23 40 19 assigned to stations 120 to 129
- XX 1 41 23 41 00 to XX 1 41 23 41 19 assigned to stations 130 to 149
The local exchange assigns the new range XX 1 41 33 40 15 to XX 1 41 33 40 24: these
numbers are assigned to stations 150 to 159.
As described below, the dialing plan does not provide for:
- use of the whole DID range available; in fact, in order to route a DID number to a called
station, the system analyzes if the last 4 digits that the number received from the network
and the DID sequences XX 1 41 23 40 10 and XX 1 41 33 40 15 have in common, the
range of the last 4 digits 40 15 to 40 19.
- transmission of the exact number of the caller (see "ISDN services") because the system
would require two installation numbers (XX 1 41 23 and XX 1 41 33) in order to operate
correctly, which is impossible.
Additional Information
- Maximum number of entries in the modification table of DID numbers: 18
- Maximum number of digits for an entry in the modification table of DID numbers: 16.
- Maximum number of digits in a substitution number: 4.
3.16.1.2 Configuration procedure
3.16.1.2.1 Configuration
- Configuring the installation number:
• by OMC (Expert View): Dialing -> Installation Numbers
• by MMC-Station: Global -> InsNum -> Public
- Filling in the substitution table:
• by OMC (Expert View): Dialing -> DID Number Modification Table
• by MMC-Station: Num Pln -> PubNMT
- Completing the DID dialing plan:
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