Those who know me personally and at work know how much of a big believer I am in Exchange Unified Messaging for your Voicemail needs when using CUCM, but doing my CCIE Voice has given me a new appreciation of the features that Unity Connection actually has.
That's one of the great things about the CCIE's (in every track) and is one of the reasons when people poo-poo the CCIE and say things like they already know enough to be one.
While that might be true (but for most of the people who claim it who i've met, I know it's wrong) the thing is that the training itself exposes you to things you just plain may not have ever seen before and for me this has been the case with Unity Connection.
First of all, did you know your voicemail subscribers have multiple greetings? They actually have 7 different greetings they can use?
The most common is standard, as that's the one we are all used to, but there is also closed, internal, holiday and alternative. (There's a few more too but these are the main ones you would probably use in most real-world situations.)
All of the above except for closed overwrite the standard greeting if that particular case is matched, so for example, internal greetings are played when an internal caller rings, the holiday greeting plays when a particular calender holiday day is active.
You also have reasonably powerful objects in unity connection called call handlers, these allow you to gather information about callers and present it to the called party before transferring the call, for example, the caller can be asked there name and the called party can confirm they want to talk to them before being transferred through.
During a call handler, you can also dial any extension on the system and unity will attempt to transfer you to that number, you can also be transferred to a caller directory handler where you can enter the number of the person your trying to reach, Unity Connection even has its own restriction tables that prevent toll-fraud (these are set to US style telephone numbers by default so are worth updating.)
As I discover more about Unity Connection for my voice lab I will post it below.
Also, I know I have a few readers around, I am very much considering writing my own CCIE Voice lab practice labs, designed to be fiendishly hard. Let me know in the comments below if that's something you'd be interested in.