You can save your password for Office Communicator only by modifying the Windows registry.
Note that for editing Windows Registry, administrator rights are required, because it is not safe and you will perform it at your own risk.
- In Windows click on Start > Run and type in "regedit".
- In the Registry, navigate to HKEY_LOCAL_MACHINE/Software/Policies/Microsoft/Communicator.
- Right-click in the right pane and select New > DWORD (32-bit) value.
- In the Name field, type "SavePassword" (without quotes).
- Double-click the new item and type "1" (without quotes) in the Value data field.
This enables a checkbox to save the password in the Office Communicator login window. After the password is entered during login, it is saved in the registry HKCU/Software/Microsoft/Communicator/AccountPassword. This registry key stores a hash value. Changing the hash requires re-entering the password.
If after checking the box to Save Password OCS still prompts for it, try to modify the following entry:
Set it to '0'.