Yes, at least a mildly hot standby.
1. Buy and install a CallPilot 5.0 on the remote site PBX.
2. On the production CallPilot schedule an user and an application network backup to run every 24 hours.
3. Manually restore these backups to the remote CallPilot also every 24 hours.
There are many system engineering details both on the CallPilot systems and the PBX's that need to be accounted for to make this work. Get you vendor involved and Nortel directly on engineering this one. And once it's all installed: test, test, test... and document, document, document...