Disable SIP ALG for TP-Link Router (User Interface and CLI)

TP-Link (User Interface Guide) 

Note: that as this process may temporarily interrupt your internet connection and phone service, we recommend doing this in an off-peak period or outside of business hours.

Learn more about SIP ALG in our knowledge base article here: SIP ALG

1. From the router's menu, select Network > ALG Settings. On some firmware versions, this has moved to Advanced > NAT Forwarding > ALG
2. Under Application Layer Gateway (ALG), find SIP ALG and check Disable. Click save and, if prompted, restart your router.

TP-Link Disable SIP ALG (CLI: Command Line Interface Guide)

1. Press the Windows Logo Key +"R" Key on the Keyboard at the same time or click on Start button->Run to open Run program.
   • 
2. Type in cmd in the open bar and click OK
   • 
3. Type in "telnet 192.168.1.1" (192.168.1.1 is the default IP Address of the modem router, if you have changed it, please type in the matched IP) and press Enter.
   • 
4. The telnet command may not be enabled by default, please click on Start Button->Control Panel->Programs-> Programs And Features->Turn Windows features on or off, then check Telnet Client and hit OK to enable telnet command
5. In the telnet page, type in the username and password for the modem router (both are admin by default) and press Enter.
6. Type in command sh and press Enter.
7. Type in the following commands:

   • rmmod nf_nat_sip.ko

   • rmmod nf_conntrack_sip.ko]

   • 

8. And press Enter.

   • All of the above settings are temporary. Once you restart or reset the modem, the SIP ALG will be turned back on.
   • You may try the lsmod command to check if the SIP ALG is turned off or not.
9. When SIP ALG is on, the status for the following sip items will show live:

nf_nat_sip

nf_conntrack_sip

After the SIP ALG is disabled, you may not find the corresponding sip items.

3. If you want to Enable SIP ALG by telnet again, you may type in the following commands by turn:

insmod lib/modules/2.6.21.5/kernel/net/netfilter/nf_conntrack_sip.ko

insmod lib/modules/2.6.21.5/knerel/net/ipv4/netfilter/nf_nat_sip.ko