How to see Exchange Calendars from a different company?


It was asked by one of our sales people, for me to look into how we can see the Exchange calendar schedules of a business partner of ours.  This is a separate company; where they have a different Windows domain and Exchange Servers.  The 2 companies are connected via fiber and we already have some static routing rules in place to share an network application database, that is hosted at our facility.

The 2 companies already are connected via fiber and both companies have setup routing rules on our network routers to allow limited access to 1 specific application server.  This application server is hosted on our network and the other company maps a drive (with a server local user account and IP address) and installs the software on their network.  Static Routing rules are in place to ensure that information from this application is sent back and forth correctly.  The other company specifically has 'read-only' access to this application server's database.

But the specific question at hand is how to 'Share' our Exchange calendars and how we can see the other companies calendars as well.  These are 2 different Windows domains and Exchange Servers.  
We do not want the other company to be able to see our file servers or anything else.  Just Exchange Calendars(read-only, not emails.
PkafkasNetwork EngineerAsked:
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Adam BrownSr Solutions ArchitectCommented:
With Exchange 2007, you would make use of the Availability service and cross-forest Free/Busy replication for this. It's a little tricky to get working and requires some effort on both Exchange servers to get working. MS has a big document that explains the whole thing here: has some additional information you may want to look at.

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The quickest and easiest way would be to use OWA.

If OWA is enabled/setup in exchange...

Setup some basic AD/Exchange accounts for these users.

Give them Read Permissions to the calendars you want to share or allow them to see

Provide the remote users with their logon Ids and passwords

Then all they have to do is use an OWA URL for the shared calendar
https://<server name>/owa/<SMTP address>/?cmd=contents&module=calendar

SMTP Address being the shared calendar

They will be asked to logon

once done they can view the calendar
PkafkasNetwork EngineerAuthor Commented:
I like that idea apache09.

I will run it past my superioirs and see if they are ok with that as well.  
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PkafkasNetwork EngineerAuthor Commented:
The onlyu thing is that our users would liek to see the other companie's avaialbeilty as well.  Hence the other company will have to do the same fo our users and we wil have to logon via OWA for the other comapny.

Althogh doing things via OWA might be 1 option, some users might find that process to be cumbersome(to go between Outlook and then teh OWA).  Some users might want to just have one application to see everything.  If we wanted to go that route what would be invovled with that?

That is having our users to see the other company's calendar availabiltiy and to allow this other company to see our calendar availability?
If OWA is not an option

The only possibel alternative i could suggest then would be to j ust publish the Calendars to Office Online.
ONce the calendar is published to office online, you can choose to to share it with.

Since its only a published calendar, not a shared calendar, it will be view only

Publishing calendar to is built into outlook 2007/2010, so each user/calendar can have it push/publish the calendar at specified intervals

PkafkasNetwork EngineerAuthor Commented:
The above process still would make our users open 2 different programs to view calendar information.

I was thinking more along the lines of viewing a user's calendar information(from another company) in our Outlook?  is there a way to do that in a safe and security conscious way?

I knwo it was possible in novell GroupWise(that is what both companies used before).  But now both comapnies are using Microsoft Exchange.

You would basically have to setup the additional mail accounts in the users profiel using POP,IMAP, or HTTP
To allow them to see the calendar.

However, they would also have read access to mail/contacts/ and other items associated to thate Exchange account

So no, not calendar only.
Adam BrownSr Solutions ArchitectCommented:
The availability service is the way you are supposed to do this. It is purpose built for sharing calendar info between organizations in outlook. No need for multiple programs. The calendars are shared and visible from each users own outlook profile. Look at the links I gave earlier.
PkafkasNetwork EngineerAuthor Commented:
I will have to reasearch this further when I have ti me.  Thank you every one.  
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