This article explains how to disable SIP ALG on the ASUS DSL-N16 and ASUS DSL-AC55U modem router.

Although this guide was written with the ASUS DSL-N16 router in mind, the guide below should be applicable to other ASUS routers, such as the ASUS DSL-AC55U.

1. Fire up a browser (Firefox, Chrome etc) and go to 192.168.1.1 (this is the default IP address)
   The default username is admin and the default password is admin
   Once logged in for the first time you may be prompted to change your password.
2. Under the Advanced Settings side menu click on WAN
3. Click on NAT Passthrough tab on the top sub menu
   
4. Set SIP Passthrough to Disable
   
5. Click Apply

You can purchase the ASUS DSL-N16 from the SureVoIP Store.

The ASUS DSL-AC55U can be purchased from the SureVoIP Store also.

Further information can be found at ASUS documentation.