SIP ALG is located in (via the web interface):
- Go to Advanced Settings / WAN on left side.
- From the tabs across the top, choose NAT Pass through.
- Change SIP pass through to "Disable." Hit apply.
If your router does not have an option to disable SIP Passthrough then read on...
To disable the SIP ALG manually, you enable telnet to the device via the WWW interface.
Telnet to the device (from a command line enter "telent 192.168.1.1" or the appropriate IP address for the device.)
Issue the following commands:
nvram get nf_sip (It should return a "1")
nvram set nf_sip=0 nvram commit Reboot