If you access your Office Communications Server environment from desktops that are not part of a corporate Active Directory then you will have to enter a password every time you log on to Office Communicator.
But wait, you can enable a Save Password Dialog Box in Communicator with a simple registry Key entry. Here is how:
Open the Registry editor and create the following RegDWord Key under "HKLM/Software/Policies/Microsoft/Communicator"
Create the RegDWord value of "SavePassword" and set it to "1"
Restart the MOC client and you will now see the Save Password Checkbox! Enable this option and sign in. Communicator will not prompt you for your password until the next time you have changed it. The password is stored securely in the registry.