A mobile communication device operating in a wireless local area network (WLAN) of a communication network maintains an inter-enterprise voice call via its WLAN interface (e.g. 802.11/VoIP/SIP) with another communication device in the communication network. During the voice call, a handover of the voice call from the WLAN to a wireless wide area network (WWAN) (e.g. GSM/GPRS) is identified. In response to identifying a handover indication, the mobile device causes a request message (e.g. a SIP INVITE message) to be sent over the WWAN to the conferencing gateway for establishing a first connection leg through the WWAN via its WWAN interface with a conference room of the conferencing gateway. The mobile device also causes a re-routing message (e.g. a SIP REFER message) to be sent to the communication device, so that a second connection leg between the communication device and the conference room may be established.