About the dial plan issue: as long as the extensions are unique, the Unity servers can be in the same dialing domain. The extensions can be different lengths, they just need to be unique. And of course, the Unity servers need to be integrated with the same "phone system" (lots of hand-waving here, as I know very little about CallManager.)
But if the extensions are not unique, then the Unity failover pairs really do need to be in separate dialing domains. In this case, you won't be able to use a single unity server to do the cross-server logon. The cross-server logon feature requires that the Unity servers all be in the same dialing domain. This doc explains more about the cross-server logon feature: http://www.cisco.com/en/US/docs/voice_ip_comm/unity/5x/networking/guide/ex/5xcunet030e.html
The docs don't explicitly say that only one Transport Event Sink is required, but having more than one doesn't help anything. The thing that will help the most is being careful in choosing the domain name for the Event Sink.
The following section of the Networking Guide talks about the figuring out the domain name to use for the Event Sink:
The docs don't say, but I think in practice people generally create a new recipient policy in Exchange, and specify the new policy when installing the Event Sink. For example, say the default recipient policy is "cisco.com", I think what people generally do is create a recipient policy like "voicemail.cisco.com" and use that when setting up the Event Sink. That way, only voice messages will be coming into the Exchange org with the domain name "voicemail.cisco.com" in the address. The Event Sink will see those, and route them to the Voice Connector mail box.
SIP traces provide key information in troubleshooting SIP Trunks, SIP
endpoints and other SIP related issues. Even though these traces are in
clear text, these texts can be gibberish unless you understand fully
what they mean. This document attempts to br...
Please find the attached HTML document, download and open it on your PC.
This provides an easy to use form where you simply answer a few
questions and it will render the proper jabber-config.xml file for you
to copy/paste. There is built in logic to verif...
CUCM Database Replication is an area in which Cisco customers and
partners have asked for more in-depth training in being able to properly
assess a replication problem and potentially resolve an issue without
involving TAC. This document discusses the bas...