A gateway device and method for establishing Voice over Internet Protocol (VoIP) communication includes setting coding methods of the VoIP, and setting quality of service (QoS) parameters corresponding to each coding method. In response to dialing a VoIP phone call from a local user terminal, a Session Initiation Protocol (SIP) session is initiated to determine a coding method. QoS parameters corresponding to the determined coding method are parsed to generate a request packet. The request packet is sent to base station to request for establishing a VoIP phone call. The VoIP phone call is established between the local user terminal and a remote user terminal by sending the VoIP packets through the base station to the remote user terminal.