Nortel Meridian 1 Succession 1000M Installation And Configuration Manual page 403

Note: The first number of the default numbering plan is preprogrammed
as 2200. The remaining numbers in the default numbering plan are
assigned in software. These numbers do not become active, however,
until you select the numbers during the telephone activation procedure.
The digit "7" in the default numbering plan is programmed with many system
features to assist you in configuring the Small System. If you have the
Meridian Mail card option software, it automatically configures user
mailboxes to correspond with the 2200 numbering plan. In addition, the
preprogrammed Meridian Mail queues in the Meridian Mail software match
the default data on the system.
Preprogrammed data
Small System Installation and Configuration
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