When subscribers attempt to listen to the voice messages in the Cisco Unity 4.x, some subscribers are always prompted to enter their name, password, and domain name. The rest of the subscribers can access voice mail through ViewMail for Outlook (VMO) without any prompts.
In order to resolve this issue, it is a must to use Distributed Component Object Model (DCOM) to authenticate to the Cisco Unity server in order to play the messages. Complete these steps:
Run DCOMCNFG from a command prompt from the Windows XP machine.
Under Component Services, click Computer. Then, right-click My Computer, and choose Properties.
Click Default Properties.
Check Enable Distributed COM on this computer.
Under Default Distributed COM Communication Properties, choose Connect for the Default Authentication Level and Identify for the Default Impersonation Level.