SIP (Session Initiation Protocol) is the protocol used to facilitate VoIP calls and its features, such as call presence, device registration, and managing audio sessions. This is the magic that makes VoIP calls happen!
As it relates to SIP, ALG (Application Layer Gateway) acts as a proxy that re-writes destination information within the SIP traffic to improve connectivity in specific network configurations.
Why should it be disabled?
While SIP ALG sounds like it should improve consistency, it does the opposite a majority of the time. Most network configurations are negatively impacted by having SIP ALG enabled. SIP ALG will artificially change the destination of SIP traffic and cause it to terminate at an address that does not exist on the network. This leads to the symptoms listed below.
- Dropped Calls
- No incoming Calls
- Registration Issue
- The Phone keeps ringing after you pick it up
How to disable SIP ALG
Most modern routers/firewalls come with the ability to toggle SIP ALG on/off. If you work with an IT professional, you should contact them to request that SIP ALG be disabled on your device.
If you manage your office network, simply looking up the model of your router + SIP ALG will likely yield a result on how to disable the setting. Our support team can also assist you with finding relevant information that will guide you through disabling SIP ALG on your router.
Once disabled on your network, our Support team will confirm that to be the case. We will then monitor the situation moving forward to see if any of the symptoms return.
SIP Network Optimization
Learn more about SIP protocols, ports, SIP-aware devices, and QoS.