When any external or Internal user calls a user in OCS-UM enabled environement, The OCS Server selects the UM server for Voice mail facility. Following steps explain how does this happen -
- OCS will determine SIP Address of the dialed number
- It will check if the user is enabled for Unified Messaging. The attribute it will query is "MSExchUMEnabledFlag"
- If the user is enabled for UM, It will query proxyAddress (EUM type) of the user.
- OCS Server will find out the dial plan name from EUM Proxy Address
- OCS Server will query Dial Plan object to find out the list of Exchange UM servers assigned to it.
- OCS Server will select the Exchange UM Server based on routing logic
- If it doesn't get response from the first Exchange UM Server it selected, It will select the second Exchange UM Server
Routing to UM server involves determining which UM server is able to service the request of the user and how to route the call to that particular UM server
The routing feature has following characteristics:
Determine the UM server to route the call.
If more than one UM server is linked to the dial plan then try a different server if the first server does not respond.
Generate request that UM can understand and process.
Establish media session between UM server and UC client.