Rebuilding IM & Presence Servers Failing

Now that IM & Presence servers are configured as subscribers in CUCM, rebuilding them isn't quite so straight forward. If you just try reinstalling them then you'll get a nice unhelpful error message like the below:

To avoid this, within CUCM you must first delete the Presence Redundancy Group that contains the IM & P servers, then delete the IM & P servers. You may also need to bulk update all End Users to disable "Enable User for Unified CM IM and Presence". Then you'll be able to successfully reinstall the IM & Presence servers without it failing.

Also watch out for bug CSCus27634, which affects certain versions of IM & Presence 10.5, it results in the Cisco Presence Engine refusing to start due to it crashing. If you look the traces for the Cisco Presence Engine you'll see something a bit like this:

*** glibc detected *** /usr/local/pe/bin/pe: free(): invalid next size
(fast): 0x0ada0010 *** ======= Backtrace: =========
/lib/libc.so.6(+0x70b91)[0x787bb91]

Jabber for Windows/Mac With Telephone Number as Username

Jabber for Windows & Mac assumes that the sAMAccountName & userPrincipalName in Active Directory provide the correct username. However if in CUCM you're using the telephoneNumber or ipPhone field as the username (which I've seen many times!) Jabber won't work properly. When you view a contact in Jabber the IM address will show the incorrect username, for example dave@example.com instead of 4321@example.com.
In the days of CUPC you could edit the LDAP attribute mappings in the CUPS GUI, but for Jabber you have to create an XML file to configure the attribute mappings. Assuming you're using the telephoneNumber field as the username, create a file in UTF-8 encoded text file named jabber-config.xml containing the following:

<?xml version="1.0" encoding="utf-8"?>
<config version="1.0">
 <Directory>
   <UserAccountName>telephoneNumber</UserAccountName>
   <DomainName>telephoneNumber</DomainName>
 </Directory>
</config>

Upload this file to all your TFTP servers & restart the TFTP service on them. Now when Jabber loads it will download this file & assign the correct LDAP attribute mappings.
There's a bunch of other settings for Jabber that you can only configure via an XML file, fortunately Cisco have released a tool to help automate this process.