This page has been moved, the new location is How to Disable SIP ALG on the DrayTek Vigor Series Routers (firmware 3.8.5 and newer).

How to Disable SIP ALG on a DrayTek Vigor Router

Please refer to the guide appropriate for the firmware version your router is running:

How to Disable SIP ALG on the DrayTek Vigor Legacy Models (firmware pre-3.8.5) - generally applicable for all DrayTek models
How to Disable SIP ALG on the DrayTek Vigor Series Routers (firmware 3.8.5 and newer) - applicable for newer models which are running firmware version 3.8.5 and newer