We are installing two Unity clusters to support two Dialing domains. We also need to integrate these clusters to other Voice Mail systems using VPIM. I need some directions on the VPIM setup:
1. How many voice connectors do I need. I think I just need one to support any number of clusters as long as they are digitally networked.
2. How many Transport event sinks do I need. Some document specify that I need one event sink per dialing domain but I am not sure if this is true and why do I need two.
3. Also we need single logon. Do I need multiple (one/dialing domain) front end unity servers to support that.
Following is more information on the Event Sink from an email I saved from one of our engineers. It helps to explain the importance of choosing the right domain name for the Event Sink.
Incoming VPIM messages hit the domain as @.com - for example [email protected].
There is no subscriber with a proxy address of [email protected]. In order for this message to get routed to the Unity Voice Connector for Exchange to be processed as a Unity voice message and delivered to the intended subscriber, you install the Unity VPIM Event Sink when installing the Voice Connector and selecting the VPIM feature. The event sink gets put into Exchange with all of the other event sinks that Exchange already has. You are asked for a domain name when you install the event sink, and this is the domain name that the Unity VPIM event sink will be watching for. If the domain name you enter is "company.com", then any message entering the Exchange org addressed to @company.com will be re-routed to the Voice Connector. The Voice Connector looks up 5551212 against Unity dtmfaccessid property on Users in AD and sees that 5551212 is John Doe, then re-routes the message to John Doe as a Unity Voice Message.
So you want to make sure that inbound VPIM voice messages intended for Unity subscribers get routed to the Voice Connector, but at the same time, you don't want any other message to get routed to the Voice Connector because the Voice Connector won't be able to do anything with it. So you can see that, if you have messages entering your Exchange org addressed to @company.com and they're intended for some other voice mail system, they'll get hijacked off to the Voice Connector and won't make it where they're supposed to. That's why it's best to use a more specific domain name, such as "@unity.company.com", so you can configure the event sink to only re-route messages addressed to @unity.company.com to the voice connector.
This is something to keep in mind not only if there's another VPIM voice mail system in the picture, but if there's *any* reason that an inbound SMTP message to @company.com would be expected where it's not an inbound VPIM message to a Unity subscriber. For example, if somebody has a proxy address of [email protected] and the event sink is configured for "company.com", this message would get re-routed to the Voice Connector, the Voice Connector would not find a Unity id on a User of 341, and the message would not make it to the person who has a proxy address of [email protected].
One more point about this is that the domain you configure the event sink for applies to that domain and all sub-domains. So if you use "company.com" and a message comes in addressed to @subdomain.company.com, this message would also get routed to the Voice Connector. If the event sink is configured with a domain of "unity.company.com" and a message comes in addressed to @subdomain.company.com, then everything is fine, because subdomain.company.com is not a subdomain of unity.company.com.