help • 8 Numbering plans and time configuration • Numbering plans
8.2 Numbering plans
Numbering plans are needed to link your organisation’s external phone numbers to internal extension numbers, so that your extensions can be reached from the global public telephone network (PSTN). In a numbering plan, an external phone number can be linked to only one extension. This can be any type of extension, e.g. a user extension, a group extension, a queue extension, a TBR, an LBR etc.
Within a numbering plan scheme, up to 99 different numbering plans can be created. In each of these numbering plans, you can configure your organisation’s reachability for a specific situation. For example, a numbering plan can be created to manage your organisation’s reachability during opening hours, other numbering plans can be configured for closing times, lunchtimes, holiday periods, emergencies, etc.
For each numbering plan scheme, only one numbering plan can be enabled at any time. A numbering plan scheme can be activated by a time configuration, a holiday schedule or a manual override.
There are three different ways to activate numbering plans:
*Automatic activation via time configuration, see 8.2.5 Activating numbering plans automatically by specific days
*Automatic activation via holiday schedule, see 8.2.4 Activating numbering plans automatically by holidays
* 
A holiday schedule activation will override any time configuration activation. A manual override will override the time configuration and holiday plan.