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Support for Multiple Exchange Servers

Can 1 Unity box support multiple Exchange servers?

For example:

Company A has an Exchange Server

COmpany B has an Exchange Server

Company A wants to centralize, by having 1 Unity Server (Both Companies will require Unified Messaging)

Is this possible? Or will we have to collapse Exchange servers first?


Re: Support for Multiple Exchange Servers

Hi -

If the Exchange servers are in the same Exchange organization (AD forest) and same Exchange administrative group (routing group); and there is less than 40 ms. between Unity and the Exchange servers (i.e. LAN speed), you should be fine. Unity can talk to multiple Exchange servers.


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Re: Support for Multiple Exchange Servers

THanks for the post. Is that 40ms RTD or one way?

Re: Support for Multiple Exchange Servers

well, I would debate this a little. I know between Unity Failover and Primary, and also CCM pub and sub, the roundtrip has to be less than 40ms rountrip for the SQL databases to replicate.

For Unity to communicate to the message server, I dont remember seeing 40ms round trip times. Cisco really does not support Exchange one location and Unity in another location. They normally have to be next to each other on the LAN. You can however split Unity Failover and Primary if 40ms threshold is within reason.

I cant seem to find any documenation on this. The only thing I could see would be delayed MWI's if you have Unity split off from Exchange (HQ-datacenter).

Exchange in the same Org, can be setup in AD for sites and services with SMTP links between the sites to deliver messages between the sites effciently. So if Subscriber A forwards a message to Subscriber on Exchange B, Exchange A takes the message, use MTA and transfer the messages to next exchange server.

errrrr am I off today?

Community Member

Re: Support for Multiple Exchange Servers

What if the scenario is Unity cluster to support two or more exchange servers that belong to two seperate organizations. Will Unity be able to support voice messaging and Integrated Messaging?

If so, will it make any difference if the exchange servers run versions 2000, 2003 or 2007?

Re: Support for Multiple Exchange Servers

You can do this, but the domains have to be trusted. If they are not trusted in AD, then Unity can not support both Exchange/Domains. Unity is a memeber server in AD domain. So if Unity is a member of AD domain A, and Domain B is not trusted to domain A, there is no way to support this type of setup.

Same for Digital networking. they have to be in the same domain or trusted between domains

Re: Support for Multiple Exchange Servers

I've done this sort of configuration before on Unity 4.05. Domain A had Unified messaging where Unity and serviced users on Domain A's Exchange server and users on a separate Exchange Server in Domain B. A domain trust between the domains allowed the Global Catalogs to see each other and the permissions wizard was run on both servers to enable access for the service accounts.

I have a new scenario to ask about:


Domain A and Domain B have a domain trust. Domain A is W2K3 native and Domain B is W2K native.

Domain A and Domain B will run Unity Unified Messaging 5.0 with failover on their own MS Exchange 2003 environments.


1. Can I digitally network them together? I think so but can anyone confirm?

2. If the above is true, Unity Bridge should be able to use either as a bridgehead, yes?

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Re: Support for Multiple Exchange Servers

Based on the post above,

If I have Unity 5.X pointing to trusted Domain A and trusted Domain B both Exchange boxes are in the same Exchange organization.

Does it matter if one exchange server is running 2003 and the other is running 2007?

Re: Support for Multiple Exchange Servers

You will need have (1) unity server per version of Exchange.

Unity 5.x will support 2000/2003 only (per server)

Unity 5.x will support 2007 only.

You cant mix and match Exchange versions. Only on 2000/2003 you can mix.

Within the Exchange Org, you can have a mix of Exchange versions, but only if you follow the rules.

If you Exchange Org *started* as 2007, you can not install a 2000/2003 Exchange server into the Org.

If your Exchange Org *started* as 2000/2003, you can add more of the same versions AND Exchange 2007.

Because MSFT changed some coding in 2007, Unity can not communicate to Exchange as it did with 2000/2003. The MAPI client (i believe) was changed and it had to be changed between 2007 and Unity 5.x.

hope this helps

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