SIP (Session Initiation Protocol) ALG (Application Layer Gateway) is a feature in many routers/hubs which inspects any VoIP (Voice over Internet Protocol) traffic to prevent problems caused by firewalls and if necessary, modifies the VoIP packets. Routers and some broadband hubs will often have SIP ALG enabled as a default setting.
If SIP ALG is enabled, it can affect some of your services, like BT Cloud Voice SIP and Digital Voice for Business. It can interfere with:
- Signalling on incoming and outgoing calls.
- Registering on the platforms.
- One way audio transmission.
It can also cause voice quality issues.
The feature SIP ALG can also be known as SIP Aware or SIP Transformations. This feature must be disabled when using BT Cloud Voice SIP and Digital Voice for Business.
Find out how to switch off SIP ALG on BT Cloud Voice.
Find out how to switch off SIP ALG on Digital Voice for Business.