Voice over WLAN vendors have asked the IEEE to start a VoWLAN-specific study group: Currently, aspects of 802.11 related to the needs of VoWLAN are broken out in 802.11e (quality of service or packet prioritization and scheduling), 802.11f (inter-access point communication, which includes fast handoff of authenticated users), and 802.11i (encryption). Voice calls need very fast handoff as users roam, and the current standards are apparently not focused specifically enough for some vendors.
As expected, Cisco has its own proprietary plans, yadda yadda yadda.