Specifications

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Cisco Unified Wireless IP Phone 7921G Administration Guide for Cisco Unified CallManager Release 4.1, 4.2, 5.0
OL-10802-02
Chapter 2 An Overview of the Voice Over IP Wireless Network
Components of the VoIP Wireless Network
Related Topics
• Authentication Mechanisms in the Wireless Network, page 2-19
• Interacting with Cisco Unified CallManager, page 2-24
• Voice Over IP Wireless Network Configuration, page 2-27
Authentication Mechanisms in the Wireless Network
Before a wireless device can communicate on the network, it must authenticate
with the access point or the network by using an authentication method. The
wireless
IP phone can use these authentication methods in the WLAN:
• Open Authentication—Any wireless device can request authentication in an
open system. The access point that receives the request may grant
authentication to any requestor or only to requestors on a list of users.
Communication between the wireless device and access point could be
non-encrypted or devices can use WEP keys to provide security. Devices that
are using WEP only attempt to authenticate with an access point that is using
WEP.
• Shared Key Authentication—The access point sends an unencrypted
challenge text string to any device attempting to communicate with the access
point. The device that is requesting authentication uses a pre-configured WEP
key to encrypt the challenge text and sends it back to the access point. If the
challenge text is encrypted correctly, the access point allows the requesting
device to authenticate. A device can authenticate only if its WEP key matches
the WEP key on the access points.
Shared key authentication can be less secure than open authentication with
WEP because someone can monitor the challenges. An intruder can calculate
the WEP key by comparing the unencrypted and encrypted challenge text
strings.
• WPA Pre-Shared Key (PSK) Authentication—The access point and the phone
are configured with the same authentication key. The pre-shared key is used
to create unique pair-wise keys that are exchanged between each phone and
the access point. You can configure the pre-shared key as a hexadecimal or
ASCII character string. Because the pre-shared key is stored on the phone, it
might be compromised if the phone is lost or stolen.