A first wireless AP of a WLAN in a first subnet segment of a network has both a local ESSID and a global ESSID for mobile devices to associate with it. Similarly, a second wireless AP of the WLAN in a second subnet segment of the network has both a local ESSID and the global ESSID for mobile devices to associate with it. The global ESSID is used for accessing a global VLAN which spans across the first and the second subnet segments. Initially, a mobile device associates with the first wireless AP using the local ESSID. Just prior to a VoIP session, the mobile device reassociates with the first wireless AP using the global ESSID. If a handoff to the second wireless AP is made during the VoIP session, the mobile device associates with the second wireless AP using the global ESSID.