I have bought a D-Link DVG-6004S VoIP gateway so I can use SIP features using 3CX. I have been trying to configure it to use SIP phone feature for 4 SIP outlets. But I could not configure it. I have also tried to transfer my office telephone on this gateway so I can use it as a router for normal telephone calls. I have been successful to define several extensions, and make calls using 3CX softphone. I have also received calls, but I cannot hear or speak (no audio transfer). Has anyone had any experience using a D-Link gateway with 3CX? How should I configure the settings? Which parts are essential?