Nortel Meridian 1 Option 11C Planning And Installation Manual page 317

Pre-programmed data Page 317 of 408
The digit "7" in the default numbering plan is programmed with many system
features to assist you in configuring the Option 11C system. If you have the
Meridian Mail card option software, it automatically configures user mail
boxes to correspond with the 2200 numbering plan. In addition, the
pre-programmed Meridian Mail queues in the Meridian Mail software match
the default data on the Option 11C system.
Option 11C Planning and Installation Guide