Knowledgebase: Router & Network Help
How to Disable SIP ALG by Router Model
Posted by Marlon Sibrian, Last modified by Albert Diaz on 28 January 2020 04:51 PM

Listed below are the common methods for disabling SIP ALG for common devices used.

If your device is not listed we recommend you contact the manufacturer or consult the manual to see if your device supports disabling SIP ALG and the instructions as to how to do it.


How to Disable SIP ALG


  • Use the following command: no ip firewall alg sip

Arris Gateway

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


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


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

AVM Fritz!Box

  • No option to disable SIP ALG.


  • Find 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)

  • Find 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


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


  • For Vigor2760 devices use the ALG feature Findd 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’.


  • Find 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.


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


  • Locate 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 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, under Network/Configuration/Settings.
  • Disable SIP ALG.

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