SIP ALG

SIP ALG (Application Layer Gateway) is a feature found in most routers which inspect 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 Busy Lamp Field (BLF) and Message Waiting Indicators (MWI).

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

Guidance on disabling SIP ALG on popular routers:

• ASUS DSL-N16 and ASUS DSL-AC55U
• BT Business Hub
• BT Home Hub
• Cisco IOS
• D-Link
• DrayTek Vigor (all models) - including end-of-life models
• DrayTek Vigor firmware 3.8.5 and newer
• Huawei HG633 (also known as the TalkTalk Super Router)
• Juniper JunOS
• Netgear
• Plusnet Hub One
• Sky Hub
• SonicWALL
• Technicolor TG582n and TG589vn V3
• Technicolor TG589VAC and Technicolor TG588v v2
• TP-LINK
• TP-LINK Archer D2 and TP-LINK Archer D7
• TP-LINK TD-W8960n and TP-LINK TD-W8968
• TP-LINK TD-W9970
• TP-LINK Archer VR900
• Virgin Media Super Hub
• Vyatta

To be added:

• Linksys
• WatchGuard XTM
• ZyXEL