When you add a Unified Communications Module running Voicemail Pro to a system, the system automatically adjusts to use that voicemail server. However, you should confirm this by checking the Voicemail Type and Voicemail IP Address settings in the IP Office configuration.
To set the voicemail server address:
1.Start IP Office Manager and receive the configuration from the IP Office system.
2.Select 
System.
3.Select the Voicemail tab.
•Check that the Voicemail Type is set to Voicemail Pro on UC Module.
•! WARNING: IP Address
By default, when a configuration set to Voicemail Pro on UC Module is loaded, the IP address shown is the IP address of the Unified Communications Module. If for any reason, the Voicemail Type is changed, when set back to Voicemail Pro on UC Module, set the IP address to 169.254.0.2. This is the internal private IP address used for connection between the IP Office and the Unified Communications Module.
•In the Voicemail Channel Reservation section, the number of channels will be 4 plus any additional channels licensed, up to 40 maximum. You can license the Unified Communications Module up to a maximum of 20 ports when running Voicemail Pro and one-X Portal for IP Office or a maximum of 40 ports when running just Voicemail Pro. For IP Office Subscription mode systems, the maximum number of supported ports are automatically available.
4.Save any changes back to the IP Office system.