If you are experiencing one way audio issues disable this feature first, reboot your IP phone then try making another call. If you are wondering whether you should turn your SIP ALG (Application Layer Gateway) on or off, the short answer is – keep it off.
With the SIP session helper disabled, the FortiGate unit can still accept SIP sessions if they are allowed by a security policy, but the FortiGate unit will not be able to open pinholes or NAT the addresses in the SIP messages. SIP ALG (Application Layer Gateway) is a mechanism found in most routers that rewrites packets transmitted across the device. Fortigate SIP ALG / Fortinet SIP ALG. Posted on May 1, 2011 by keithcroxford FortiOS has two features that can modify the SIP headers and SDP parameters.
Since this is not the conventional factory setting for a router, you need to disable SIP ALG by either getting in touch with your VoIP provider or following a set of instructions developed for your specific router model. Disabling SIP-ALG is an essential part of configuring the firewall on your router and optimizing it for 8x8 service, which is why routers sold by 8x8 come preconfigured with ALG disabled.
Some background facts: this issue started prior to installing the Fortigate but they chose to wait to troubleshoot it. Disable SIP ALG -- Fortinet / Fortigate .
Navigate to the web interface-> Select Configuration-> Select NAT-> Select ALG-> Disable SIP ALG. SIP ALG ===== FortiOS has two features that can modify the SIP headers and SDP parameters. Almost all routers include a feature called SIP ALG, and are delivered with this feature enabled by default. Certain protocols are processed by the application layer gateway (ALG) and rewritten to allow better flow through a firewall or when NAT (Network Address Translation) is employed. If you are experiencing one way audio issues disable this feature first, reboot your IP phone then try making another call. 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. DD-WRT The first feature is called the “SIP Session Helper”.
D-Link: In 'Advanced' settings --> 'Application Level Gateway (ALG) Configuration' un-tick the 'SIP' option. FortiGate VoIP solutions: SIP describes FortiGate SIP support. They have replaced the phones, and both have tested good on another network. You might want to disable the SIP session helper if you don’t want the FortiGate unit to apply NAT or other SIP session help features to SIP traffic. Many ALGs (including Cisco's) have bugs which cause call flow and registration failures.
We have turned off all SIP ALG options and restarted the firewall (100e). The first feature is called the “SIP Session Helper”. Example FortiGate Voice branch office configuration describes how to configure a FortiGate Voice-80C unit to operate in NAT/Route mode and provide basic UTM and SIP The SIP protocol is one of several protocols managed by this system. An Application Layer Gateway, or ALG, could help in solving NAT related problems, but in our experience, most ALG implementations are wrong and break SIP. Regarding SIP ALG. The telecom provider looked at the traffic from their site and pointed to turning off the SIP ALG.