Chand,
Setup your WLAN into a Static network so that you ca fix the IP of your CPE in reference to your Proxy server, “how does we could reach the numbering and addressing issues like a fixed IP for the CPE”… “how could we control the QoS for VOIP”, make a bandwidth management of your wireless and your wired, this will ensure QoS of yor Voip no mattter how many PCs or Laptops who wants to connect to your CPE base..