SIP ALG (Application Layer Gateway) is a feature which is enabled by default in most Huawei routers and inspects VoIP traffic as it passes through and modifies the messages on-the-fly.

In few situations this is useful, but in most situations SIP ALG can cause problems using the service. Very often, SIP ALG is poorly implemented causing VoIP messages to be modified in a harmful way or simply corrupts them. In such cases you may experience issues registering your handset, one-way or no audio, unable to receive calls, and issues with BLF and Message Waiting Indicators.

For our Hosted VoIP service, including out Single User services, SIP ALG must be disabled on your Huawei router.

This article explains how to disable SIP ALG on the Huawei HG633 modem router. This router is generally supplied by TalkTalk to consumers.

Although this guide was written with the Huawei HG633 router in mind, the guide below should be applicable to similar Huawei routers.

This router is also known as the TalkTalk Super Router.

1. Fire up a browser (Firefox, Chrome etc) and go to 192.168.1.1 (this is the default IP address)
   The default username is admin and the default password is admin
2. On the main menu click on the Internet tab
   
3. On the left-hand menu click on Port Forwarding
   
4. Under ALG uncheck the Enable SIP ALG box
   
5. Click Save

We suggest purchasing a router suitable for business use, such a DrayTek Vigor router. Contact SureVoIP Sales or call 0330 445 0000 for a quote.

• As this is a router supplied by TalkTalk to their consumer customers, public information may not be available. Please contact your internet provider for further information.
• https://www.talktalk.co.uk/shop/broadband/super-router - TalkTalk Super Router product page.