Cisco Unified IP Phones use the same APs as wireless data devices. However, voice traffic over a WLAN
requires different equipment configurations and layouts than a WLAN that is used exclusively for data traffic.
Data transmission can tolerate a higher level of RF noise, packet loss, and channel contention than voice
transmission. Packet loss during voice transmission can cause choppy or broken audio and can make the phone
call inaudible. Packet errors can also cause blocky or frozen video.
Because the Cisco Unified IP Phone 9971 is a desktop (not mobile) phone, changes in the local environment
can cause phones to roam between access points and can affect the voice and video performance. In contrast,
data users remain in one place or occasionally move to another location. The ability to roam while maintaining
a call is one of the advantages of wireless voice, so RF coverage needs to include stairwells, elevators, quiet
corners outside conference rooms, and passageways.
The Cisco Unified IP Phone 9971 does not support Voice over the Wireless LAN (VoWLAN) via Outdoor
MESH technology (Cisco 1500 series).
No support exists for third-party access points because no interoperability testing occurs with these access
points. However, if the access point supports the key features and follows the standards, the Cisco Unified
Wireless IP Phone is compliant.
Wi-Fi compliant APs that are manufactured by third-party vendors support the Cisco Unified IP Phone 9971,
but might not support key features such as Wi-Fi MultiMedia (WMM), Unscheduled Auto Power Save Delivery
(U-APSD), Traffic Specification (TSPEC), QoS Basic Service Set (QBSS), Dynamic Transmit Power Control
(DTPC), or proxy ARP.
AP Authentication and Encryption Options
Authentication and encryption schemes are set up within the wireless LAN. VLANs are configured in the
network and on the APs and specify different combinations of authentication and encryption. An SSID
associates with a VLAN and the particular authentication and encryption scheme. In order for wireless client
devices to authenticate successfully, you must configure the same SSIDs with their authentication and encryption
schemes on the APs and on the Cisco Unified IP Phone.
Some authentication schemes require specific types of encryption. With Open authentication, you can use
static WEP for encryption for added security. But if you are using Shared Key authentication, you must set
static WEP for encryption, and you must configure a WEP key on the phone.
When you use Authenticated Key Management (AKM) for the Cisco Unified IP Phone, several choices for
both authentication and encryption can be set up on the APs with different SSIDs. When the phone attempts
to authenticate, it chooses the AP that advertises the authentication and encryption scheme that the phone can
support. Auto (AKM) mode can authenticate by using WPA, WPA2, WPA Pre-shared key, or CCKM.
Cisco Unified IP Phone 8961, 9951, and 9971 Administration Guide for Cisco Unified Communications Manager
10.0
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VoIP Wireless Network Components
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