Nortel Meridian 1 Manual page 857

Note: During the upgrade procedures, transient calls, CDR information,
PRI service, and traffic report information may be lost.
The hardware required for this upgrade is provided in the Core Module
Upgrade Package. All existing equipment that will be retained must be
compatible with X11 release 21. Order replacements for all equipment that
does not comply.
Verify that any existing QPC441 3-Port Extender cards in the system are of
one of the vintages required for release 21. These vintages are: B1, D,
E (series B), E1 (series B), or F. If any existing 3PE card in the system is not
one of these vintages, replace it with a card of acceptable vintage. All 3PE
cards in the system must be of the same vintage.
Note: Refer to Product compatibility (553-3001-156) for vintage
requirements.
Before you begin the upgrade, perform an inventory to ensure that all required
equipment is available on site.
Upgrade system installation Upgrading to Meridian 1 system options
Upgrades to Meridian 1 option 81 12-93