Settings of the Extension
Proceed as follows:
•Separately for PBX base numbers
•Using the Configuration Manager (Public switched tel. networks > ISDN > Extension numbers PTP connection)
Requirements:
•Configured PBX base number
EXTENSION NUMBERS PTP CONNECTION/BUNDLING
Select the extension number/bundle for that the extensions are to be displayed/configured, provided that more then one PBX base number was configured.
Extension (DDI number)
If you want an extension number to be different from the ones used in linear call distribution, or if an extension number is needed for a different function (e.g. remote configuration, CLIP no screening), you must also enter it in the phone number list (click on 
New). You must enter all the extension numbers for a PTP connection that is not running linear call distribution.
New). You must enter all the extension numbers for a PTP connection that is not running linear call distribution.
Note: You can input up to 250 external numbers for land line and VoIP connections in the PBX. In other words, the total maximum number of MSNs, DDI numbers and additional numbers is 250.Phone number for CLIP no screening
Requirements:
•Set up phone number
•CLIP no screening switched on for the ISDN connection
Customer-specific phone number (e.g. a service phone number) that is transferred to the destination by the exchange line without its correctness being checked.
Name
The name is used for display purposes on the system phone.
Ringtone
The ringtone specifies which sequence of sounds is used to signal external calls to internal subscribers on the PBX.
NewAdds a new phone number.
DeleteDeletes the entries marked in the list.