Lancom LC-1823 Manuals page 22

In the following stages the call router is set up to control the processing
of incoming and outgoing calls. First of all you can select whether to
precede external calls with a zero. Spontaneous outside line access means
that no leading zero is required. This can be set separately for ISDN and
analog users.
Typically you will want to make calls to other people in your company

simply by entering their extension number directly. This is only
possible if you do not use spontaneous outside line access.
When using the LANCOM Business-VoIP-Router as a PBX, we recommend
that you deactivate spontaneous outside line access. This ensures that the
leading zero for external calls has to be entered, a procedure that is
familiar to users of conventional PBXs.
If you do decide to use spontaneous outside line access, the wizard also
provides this for SIP users so that all telephones are operated in the same
way.
When spontaneous outside line access is activated, the wizard

generates dialing rules to enable you to call internal numbers by
entering a leading asterisk, e.g. '*11'.
LANCOM VoIP Routers: PBX Functionalities
Chapter 3: Configuring the VoIP functions
21