What is SIP ALG and how can I stop it causing problems on BT Cloud Voice?

SIP (Session Initiation Protocol) ALG (Application Layer Gateway) is an application within many routers. It inspects any VoIP traffic to prevent problems caused by firewalls and if necessary modifies the VoIP packets. Routers will often have SIP ALG activated by default.

How can it affect BT Cloud Voice?

If its been activated, SIP ALG can stop your BT Cloud Voice devices from –

  • registering on the service
  • making internal calls
  • receiving incoming calls

As part of your BT Cloud Voice set up, we will disable SIP ALG on your BT Business Hub 5. But, if for any reason your Hub is re-set, SIP ALG will automatically be activated.

How do I turn off SIP ALG on the Business Hub 5?

Make sure you’re using a computer that’s connected to your network then –

  1. Open a browser (Internet Explorer, Firefox etc) and type or businesshub.home in the address bar. You’ll see the BT Business Hub home page.
  2. Click on ‘Advanced Settings’
  3. Enter your admin password (unless this has been changed, the default admin password can be found on the bottom of the Business Hub 5 or on the plastic pull out on its back).
  4. Click ‘Continue to Advanced Settings’
  5. Click ‘Firewall’ then ‘Configuration’ and scroll down to ‘Application Layer Gateway’
  6. Click Yes next to ‘Disable SIP ALG’ and click ‘Apply’

SIP ALG will then be deactivated on your Business Hub 5.