A packet-switched communications device in an enterprise network is provided. The packet-switched communications device has a corresponding unique identifier, such as an address or extension. The device includes a processor operable to (a) establish a secure communications session with a key generating agent in the enterprise network; (b) provide, to the key generating agent through the session, the unique identifier of the communications device; and (c) receive, from the key generating agent through the session, a secret key and a key identifier. An application server authenticates the packet switched device using the secret key. After authentication is successful, secure communications is established between the packet switched device and the application server.