How to Disable SIP ALG

Most commercial router configurations have their own set of rules for configuring SIP ALG.

To disable SIP ALG on a specific brand, locate your router model in the alphabetical table below and follow the instructions.

Disclaimer: Please consult with an IT or a network professional before making any changes to your router to avoid additional problems.


How to Disable SIP ALG


  • Use the following command: no ip firewall alg sip

Arris Gateway

  • Locate ‘Options’ under ‘Advance’ and uncheck the SIP box.
  • Apply the following credentials: 
    • UN: admin
    • Password: motorola


  • Locate ‘Class inspection_default’ under ‘Policy-map global_policy’.
  • Use the following command: no inspect sip


  • Locate ‘WAN/ NAT Passthrough’ under ‘Advanced Settings’
  • Disable ‘Passthrough’.

AVM Fritz!Box

  • No option to disable SIP ALG.


  • Locate the SIP ALG feature under NAT or router firewall settings.


  • Disable SIP ALG option is only available on BT Business Hub versions 3 and higher.

Cisco (non-ASA)

  • Locate SIP Fixup
  • On General Routers, apply the following: 
    • no ip nat service sip tcp port 5060
    • no ip nat service sip udp port 5060
  • On Enterprise-Class Routers, apply the following: 
    • no ip nat service sip tcp port 5060
    • no ip nat service sip udp port 5060
  • On Pix Devices, apply the following: 
    • no fixup protocol sip 5060
    • no fixup protocol sip udp 5060


  • Locate ‘Application Level Gateway (ALG) Configuration’ under ‘Advanced  settings
  • Uncheck the ‘SIP’ option.


  • For Vigor2760 devices use the ALG feature located under Network/NAT.
  • For other devices use a Telnet client.
  • On Windows systems: 
    • Find the Windows Start button.
    • Search for cmd: hit enter.
    • Type in telnet hit enter.

(Note: Unless you have the Windows telnet client installed, you will need to do that now by locating the Telnet Client in the Windows Programs and Features, and turning it on.)

  • Type in the username and the password in the credentials prompt.
  • Apply the following commands: 
    • sys sip_alg 0
    • sys commit
  • For Draytek Vigor2750 and Vigor2130 devices apply the following commands: 
    • kmodule_ctl nf_nat_sip disable
    • kmodule_ctl nf_conntrack_sip disable


  • Use the following commands from the CLI interface: 
    • config system session-helper
    • show system session-helper
  • Find the SIP session instance, typically indicated by #12
  • Delete #12 or the appropriate number
  • Confirm deletion by re-running ‘show system session-helper’.


  • Locate SIP ALG in the Security menu.


  • Go to the ‘Advanced’ section on the Admin page and disable the SIP ALG feature. This instruction can be used as a general Linksys router guidance.  
  • For Linksys BEFSR41 routers, go to ‘Port Triggering’ under ‘Applications and Gaming’ on the Admin page. 
    • Type in ‘TCP’ as the application.
    • Type in ‘5060’ into the Start Port and End Port for the ‘Triggering Range’ and ‘Forwarded Range’ fields.
    • Tick ‘Enable’.
    • Save and Reboot.


  • Disable SIP Helper.


  • Locate the advanced settings under Security/Firewall from the admin interface.
  • Disable SIP ALG.
  • Locate Session Limit under Security/Firewall.
  • Increase the UDP timeout to 300 sec.



  • Under the VoIP tab:
  • Check ‘Enable Consistent NAT’
  • Uncheck ‘Enable SIP Transformations’.


  • Check in the user manual for a specific model to see if you need to use Telnet commands to disable SIP ALG.


  • Use the Telnet client by typing cmd in the Windows Start menu.
  • Apply the following command: ip nat service sip sw off

UBEE Gateways

  • Go to ‘Options’ under ‘Advanced’.
  • Uncheck the SIP option.
  • Uncheck the RTSP option.
  • Click Apply.

Virgin SuperHub

  • SIP ALG cannot be disabled.


  • Go to ALG, located under Network/Configuration/Settings.
  • Disable SIP ALG.