If you have QoS enabled an QoS enabled on the wlc and the voice WLAN, then only WMM capable devices will be able to use that QoS marking. Non WMM devices will still be marked at '0'.
Take a look at page 38 in this doc.
http://www.cisco.com/en/US/docs/voice_ip_comm/cuipph/7925g/7_0/english/deployment/guide/7925dply.pdf
Thanks,
Scott Fella
Sent from my iPhone
-Scott
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