For creating standalone full duplex VoIP for S60 3rd ed devices developer are adviced to apply for two manufacturer grantable capabilities:
1) MultimediaDD 2) NetworkControl.
1) Multimedia DD is required for the Audio Proxy Server
2) NetworkControl is required for setting the the WLAN Quality of Service(SetOpt call of RSocket). The following code snippet sets the Quality of Service of our WLAn connection as VOICE. iSocket.SetOpt(KSoIpTOS, KSolInetIp, 0xE0);