This is more a theoretical question not targeting a single phone or UC version.
When using linekey reassignment, you can specify some XML like this:
<lineKey lineKey.1.category="Line" lineKey.1.index="1" lineKey.2.category="Line" lineKey.2.index="2" lineKey.3.category="Line" lineKey.3.index="1" lineKey.4.category="Line" lineKey.4.index="1" lineKey.5.category="Unassigned" lineKey.6.category="Unassigned">
<lineKey.reassignment lineKey.reassignment.enabled="1"/>
</lineKey>where the index value for category="Line" appears to map to the registations. This would allow a user to have linekey 1 tied to registration 1, linekey 2 tied to registration 2, then linekey 3 tied again to registration 1 and so on.
You can also interleave "BLF" keys between "Line" keys like this
<lineKey lineKey.1.category="Line" lineKey.1.index="1" lineKey.2.category="BLF" lineKey.3.category="BLF" lineKey.4.category="Line" lineKey.4.index="1" lineKey.5.category="BLF" lineKey.6.category="Unassigned">
<lineKey.reassignment lineKey.reassignment.enabled="1"/>
</lineKey>However, as the "BLF" keys appear to be pulled from attendant element in a top-down fashion, there isn't a way to mix "BLF" keys across mulitple registrations, e.g. linekey 2 is a BLF key from registration 1, linekey 3 is a BLF key from registration 2, and then linekey 5 is a BLF key from registration 1 again. I've not been able to find any configuration parameters that would allow for this sort of granular specificity.
So is this even possible?
