We are also facing a migration of our ca. 15000 BB devices from Domino to Exchange. Unfortunately, there is not an easy way for that, because it always means wipe + reactivate.
I know B*Nator, but I have not heard yet, that it can be used for migration. On the other hand, sometime ago we created some scripts for a merger to achieve more or less the same:
1) Send eMail to end user, that BB will be migrated at a specific date and include a (random) activation password
2) Delete BB user on the source infrastructure, create user on the target infrastructure and set the previously mailed ea password
3) Inform BB user, that migration is complete and he/she must now wipe and reactivate

We did that for ca. 2000 users in 3-4 iterations and it worked quite well.


I heard through the grapevine that RIM is evaluating the possibility of adding a feature to the Blackberry Enterprise Transporter to move users between Domino and Exchange ... unfortunately that feature won't be ready tomorrow ...


Greetings,
Neo3000

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BES 4.1.7 (20 servers) w/ Domino 7.0.3
BES 5.0.2 (6 server) w/ Exchange 2010 SP1 RU2

20000+ devices on Domino
2000+ devices on Exchange