Hi Douglas,
You probably want to work on Callmanager Groups during a maintenance window due to the fact that all phones associated to a Group will need to be reset for the changes to take place.
1. You can safely remove a Callmanager server or change the order of the servers (as noted, probably best during a slow time).
2. In this example the Callmanager Group is called CMGroup1. The order of the servers is;
1.CM2 (Sub) Phones Registered
2.CM3 (Sub)
3.CM1 (Pub)
**Change order of CMGroup1 to;
1.CM3 (Sub)
2.CM2 (Sub)
3.CM1 (Pub)
Update/Reset and associated phones will register with CM3, which is now first in the selection order.
Have a look at the following;
Updating a Cisco CallManager Group
This section describes how to update an existing Cisco CallManager group.
Procedure
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Step 1 Find the Cisco CallManager group
Step 2 Click the Cisco CallManager group that you want to update.
Step 3 Update the appropriate settings
Step 4 Click Update to save the changes in the database.
You must reset the devices that use the updated Cisco CallManager group to apply the changes. To reset all the devices that use this Cisco CallManager group, click Reset Devices.
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Tip For your convenience in resetting devices, the Reset Devices button resets all devices in the device pool that uses this Cisco CallManager group.
***Caution Resetting devices can cause calls in progress to drop.
From this good doc;
http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_administration_guide_chapter09186a00803ed653.html#wp1028530
Hope this helps!
Rob
