What is SIP ALG?
SIP ALG (Session Initiation Protocol Application Layer Gateway) is a feature built into many routers. It monitors and sometimes adjusts VoIP (Voice over Internet Protocol) call traffic to help it pass through your firewall.
Although it’s designed to improve call performance, SIP ALG can sometimes interfere with cloud phone systems like BT Cloud Voice. This can lead to problems such as devices not registering, calls failing or poor audio quality.
If you’re experiencing these issues, switching SIP ALG off can often resolve them.
What problems can SIP ALG cause?
This can stop your BT Cloud Voice devices from:
- registering on the service
- making internal calls
- receiving incoming calls
- cause voice quality issues
If you have BT Business access using the BT Business Hub 5 or any of the BT Business Smart Hubs, this won't be a problem as the SIP ALG will be disabled. However, if your BT Business Hub is reset for any reason, SIP ALG will automatically be activated. See the steps below on how to switch it off.
If you're not using BT Business access and/or BT Business Hubs or routers you'll need to disable SIP ALG on the router you're using. When you order Cloud Voice over non BT access, we'll run a test and be able to tell you if SIP ALG is switched on. If this is the case, you'll need to disable it, to be able to use your Cloud Voice service.
How do I turn off SIP ALG on my BT Business Hub?
First make sure you're using a computer that's connected to your network. Then follow these simple steps:
- Open a browser (Internet Explorer, Firefox etc.) and type 192.168.1.254 or businesshub.home in the address bar to open the BT Business Hub homepage.
- Click on ‘Advanced Settings’.
- Enter your admin password (unless this has been changed, the default admin password can be found on the bottom of the BT Business Hub or on the plastic pull-out).
- Click ‘Continue to Advanced Settings’.
- Click ‘Firewall’, then click ‘Configuration’ and scroll down to ‘Application Layer Gateway’.
- Click Yes next to ‘Disable SIP ALG’ and click ‘Apply’.
You've now turned off SIP ALG on your BT Business Hub.