There are several ways to do this but the easiest, if you have the passwords, is to log in to the unified manager. When the Login page appears it will tell you the current version..ie 3.0, 3.5 and so on. If you know the user ID and password, you can click on the on the blue System button and in the description field it will tell you the version release and build. You can also get it thourgh the phone administration if you need to under maintenence.
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