How to Disable SIP ALGs on Most Routers

SIP ALG Explained - Technical

Many of today's commercial routers implement SIP ALG (Application-level gateway) by default. While ALG can help resolve NAT-related problems, many routers' ALG implementations are brand-specific, often incorrect, and can break SIP communication.

Verify SIP ALG

You can verify if your router has SIP ALG enabled by downloading and running our SIP ALG Tester Program:

SIP ALG Tester Download

Router-Specific Instructions to Disable SIP ALG

Asus Routers: Disable SIP Passthrough under Advanced Settings / WAN -> NAT Passthrough. If your router doesn't have this option, SIP ALG may be disabled via Telnet.

AVM Fritz!Box: SIP ALG cannot be disabled.

Barracuda Firewalls: Go to Firewall -> Firewall Rules -> Custom Firewall Access Rules and disable the rules named LAN-2-INTERNET-SIP and INTERNET-2-LAN-SIP.

Billion: Navigate to the web interface: Configuration -> NAT -> ALG and disable SIP ALG.

BT Homehubs: SIP ALG cannot be disabled in the settings of BT HomeHubs but can be disabled with BT Business Hub versions 3 and higher.

D-Link: In Advanced settings -> Application Level Gateway (ALG) Configuration, untick the SIP option.

DD-WRT: No ALG function available. Consider using a public STUN server.

DrayTek: DrayTek Vigor 2760: Network -> NAT -> ALG.
Telnet commands for other devices:

sys sip_alg 0; sys commit

kmodule_ctl nf_nat_sip disable; kmodule_ctl nf_conntrack_sip disable

EE (Huawei E5330): Navigate to Settings -> Security -> SIP ALG Settings, untick Enable SIP ALG, and click Apply.

Fortinet: Fortigate: Disable SIP ALG in a VoIP Profile using:

config voip profile; edit VoIP_Pro_2; config sip; set status disable; end

Huawei: The SIP ALG setting is usually found in the Security menu.

Juniper: To check status: show security alg status | match sip. To disable:

configure; set security alg sip disable; commit

Linksys: Check for a SIP ALG option in the Administration tab under Advanced. Disable the SPI Firewall option as well.

Mikrotik: Disable SIP Helper with:

/ip firewall service-port disable sip

Netgear: Look for a SIP ALG checkbox in WAN settings. Under NAT Filtering, uncheck the option SIP ALG. Also, disable Port Scan and DoS Protection.

OpenWRT: No ALG feature available. Consider using a public STUN server.

SonicWALL Firewall: Under the VoIP tab, enable Consistent NAT and uncheck Enable SIP Transformations.

Speedtouch: Telnet commands:

connection unbind application=SIP port=5060; saveall

Tomato: Depending on the version, SIP ALG can be found under Advanced -> Conntrack/Netfilter. Uncheck it to disable SIP ALG.

TP-Link: Navigate to the web interface: Advanced Setup -> NAT -> ALG. Uncheck SIP Enabled (or SIP Transformations), and click Save/Apply.

UBEE Gateways: Go to Advanced -> Options. Disable (uncheck) SIP and RTSP, and click Apply.

Ubiquiti: Configuration tree: system -> conntrack -> modules -> sip -> disable. Or SSH into the device:

configure; set system conntrack modules sip disable; commit; save; exit

ZyXEL: Under Network or Advanced -> ALG, un-tick Enable SIP ALG and Enable SIP Transformations. For some routers, use telnet commands:

ip nat service sip active 0

ZyXEL (ZyWALL USG Routers): Go to Settings -> Configuration -> Network -> ALG. Disable SIP ALG, enable SIP Transformations, and configure SIP Inactivity Timeout.

By following these instructions, you can disable SIP ALG on various routers, which can help resolve issues related to SIP-based VoIP services. If you continue to experience problems, consider using the SIP ALG Tester to verify the changes or contact technical support for further assistance.