Exchange Server 2010 : Office Communication Server 2007 R2 Integration (part 2) - Deploying UM and OCS 2007 R2 Integration

12/8/2010 9:02:19 AM

2. Deploying UM and OCS 2007 R2 Integration

If you want to implement OCS 2007 R2 or later into your Exchange 2010 UM, your environment should consider the following requirements:

One or more OCS 2007 R2 Front-End servers.
At least one OCS 2007 R2 Mediation server connected to your PBX or phone system.
UM server roles require a digital certificate that is enabled for UM service on that server.
One or two phone numbers per OCS Location Profile—at least one for Subscriber Access and optionally one for an UM auto attendant. Particularly if you want to connect multiple office locations, you should consider at least a subscriber access number that is in the local phone range, but you can use a single UM auto attendant for the company.

Follow these steps to install OCS 2007 R2 integration for UM:

Create a UM dial plan for each of your available OCS Location Profiles:
1. The dial plan name should, for example, include information about Exchange UM and only include characters supported by an OCS 2007 R2 Location Profile (such as no spaces).
2. URI Type = SipName
3. VoIP security = Secured or SIPSecured (OCS 2007 does not support unsecured VoIP security!)
Note:

Make sure that your Office Communicator client encryption level reflects the VoIP security setting. If you configure VoIP Security as SIP Secured, you need to set it either to Rejected or Optional. If you use Secured as VoIP Security level, it must be either Required or Optional .
Configure your UM dial plan(s) with the correct OCS Location Profile Subscriber Access phone number.
Associate the UM server with the UM dial plans and make sure Startup Mode is Dual. If Startup Mode is changed, you need to restart the Microsoft Exchange UM service.
Run the ExchUCUtil.ps1 script found in the <Exchange_Install_path>\Scripts folder. The script will perform the following tasks:
1. Create one UM IP gateway for each OCS 2007 Enterprise Pool
2. Create a UM hunt group for each UM IP gateway with their respective Pilot Identifiers
3. Grant OCS 2007 servers permission to read Exchange UM objects in Active Directory
Use the Set-UMIPGateway cmdlet to configure the Port parameter of every created IP gateway to port 5061. You also use this cmdlet to disable outbound calling for all but one UM IP gateway. This is usually the gateway that is likely to handle the most traffic.
Run the Get-UMDialPlan –Id <DialPlanName> |fl PhoneContext cmdlet in EMS and remember the PhoneContext property—you'll need to create an OCS Location Profile with that exact name.
Create and configure required UM auto attendant(s). Assign them the correct UM dial plan and the access phone number from the OCS Location Profile.
On your OCS 2007 R2 Front-End server, create an OCS Location Profile in OCS 2007 R2 for the UM dial plan you created that matches the PhoneContext name.
Run the OcsUMUtil.exe tool found in the C:\Progam Files\Common Files\Microsoft Office Communication Server 2007 R2 folder. The tool will verify that OCS Location Profile and UM dial plan names match and allow you to create contacts for your Subscriber Access as well as auto-attendant access numbers.

Notes From The Field: Unified Messaging Transitioning and Extension Dialing

Gary A. Cooper

Senior Systems Architect, Horizons Consulting, Inc., United States

Within our organization, we had been utilizing Exchange Server 2007 UM in conjunction with Office Communication Server 2007 R2. This solution worked well, but we required the new features in Exchange Server 2010 UM—specifically RMS-protected Voicemail and Voicemail Preview. When we originally configured Exchange Server 2007 UM, we did not have enough Direct Inward Dial (DID) numbers for each mailbox that was UM-enabled, so we instead configured Exchange Server 2007 UM to use the auto attendant to answer all inbound calls and then to prompt the caller to select the appropriate person to contact. This worked well until we introduced Exchange Server 2010 and DID numbers .

To implement Exchange Server 2010, we had to create a new dial plan for OCS to route properly to the new UM server. This now forced each user to have two new EUM address entries after we moved their mailboxes to Exchange Server 2010 and migrated their UM to Exchange Server 2010 UM (by removing their old UM settings and re-provisioning them).

EUM: [email protected];phone-context=<NewDialPlanName>

eum:<extension>;phone-context=<Exchange2010DialPlanName>

In testing, what we found was that if a call came into OCS for a mailbox we had already moved to Exchange 2010 UM, the main number would be answered by the auto attendant in Exchange Server 2007 UM; then, when the older UM server tried to route the caller to the Exchange 2010 UM server, it would error and tell the caller "The call has failed, please press '0' (zero) for the operator or dial someone by name or extension to reach them directly." If the caller tried to dial by name or extension number to mailboxes still on Exchange Server 2007 UM, it worked without issue. Behind the scenes, Exchange UM couldn't find the migrated mailbox and would route the call back to OCS 2007 R2, which would route it back to Exchange UM, and so on, and eventually the call failed and the caller was dropped.

In working with Product Support Services, we determined that Exchange 2007 was still looking for the proxy address for its dial plan in the following format:

eum:<extension>;phone-context=<Exchange2007DialPlanName>

We determined that when the caller entered the extension (such as - 204), Exchange Server 2007 UM would search for the user in the current dial plan (the dial plan associated with the auto attendant that answered the call)—in this case the Exchange 2007 Sip_Name dial plan. It did this search by constructing the EUM address (204; phone-context=<Exchange 2007 Dial plan Name>.< Exchange 2007 Dial plan GUID >) and then searching all Active Directory users to check whether any user had this stamped in their proxy addresses. However, the migrated mailbox that has been moved to Exchange 2010 UM-has been provisioned on the new Exchange 2010 Sip_Name dial plan, so it no longer has the Exchange 2007 proxy address, and so the user object is not located.

The solution we ended up implementing was to add the legacy EUM proxy address back to the mailbox object, thus enabling extension dialing from both Exchange 2007 and Exchange 2010 UM services.