You should use the same schema version for all Communications Suite products sharing the same LDAP directory.
If you require Sun Java System Access Manager to share the same LDAP user directory with Communications Suite products, use one of the Schema version 2 modes.
You should not use Schema version 1 mode unless you satisfy all of the following criteria:
You have an earlier version of one of the Communications Suite products already installed using Schema version 1.
And, you don't want to use Access Manager.
And, you don't want to migrate your LDAP database to either mode of Schema version 2.
If Sun Java Communications Suite Delegated Administrator does not have the features you require, but iPlanetTM Delegated Administrator does, use Schema version 1 mode.
If you are installing Communications Suite products for the first time, choose the Schema version 2 mode that integrates most easily with your current DIT structure. You can choose between Schema version 2 native mode or compatibility mode. The two modes are defined in Schema Version 2 Background Information